LH engineer seriously injured at MAN 13th Nov [Archive]

speedtapeking

13th Nov 2008, 15:36

not sure what pressure a CRJ tyre is put under, but its no bigger than a kiddies bicycle tyre, even smaller perhaps,

Might only be that size still deadly. I was about 10 feet from a piper aztec wheel that let go years ago - aircraft jacked up had trouble getting the retaining nut off the axle. when the retaining nut finally came off, there was a hell of a bang at which point the whole wheel left the aircraft, one half of the wheel hub cleared the hangar without touching the floor hitting the hangar wall about 50 feet away leaving the wheel about 10ft from the aircraft. the tire was about 2ft high lying on its side with the tube still inflated. cause ? the 6 wheel hub blots all sheared, only the axle hub bold holding the wheel on.

An aztec tire is all of 30 ish psi and about a foot in diameter ... so I will let you guess what a couple of hundred psi and a larger wheel can do.....

I just hope the guy is ok at the end of it

krujje

13th Nov 2008, 15:42

so I will let you guess what a couple of hundred psi and a larger wheel can do.....

I've seen a tire burst that took off the landing gear doors.

Mr.Brown

13th Nov 2008, 17:05

Just highlights the dangers that are all around us everyday.
Yet what is probably more dangerous, remove-ing wheels without deflating
Even when fitting a new wheel; put it on and torque it up before inflating, there's a better chance the halves will stay together if the hub is cracked.

MD11Engineer

13th Nov 2008, 17:38

And deflate the tyre before you loosen the axle nut on removal....
Uninstalled tyres should only be filled if a proper safetycage is available (made out of heavy steel bars to catch flying debris), but on many line stations this is not availble. We have to inflate uninstalled wheels to get a shipset ready on our wheelchange trolley, so that we can change a wheel on a short turnaround if necessary without causing a delay.
Best wishes to the colleague.

Sir George Cayley

13th Nov 2008, 20:28

Some time since the last post. Like a previous post I know a Storm engineer and although not looking for a public identification wonder if there has been any news tonight as to his condition?

Hoping for better news.

Sir George Cayley

beamender99

13th Nov 2008, 20:50

Flight Global reporting

"A Lufthansa CityLine technician at Manchester has apparently been seriously injured while servicing a Bombardier CRJ aircraft that was bound for Hamburg on a ferry flight.
There is evidence that the individual was injured by an explosion, and unverified reports point to a possible tyre burst.
A spokesman for the German regional carrier says: "There was an incident at Manchester Airport this morning involving a technician at Lufthansa CityLine. We have no further information about what happened at the moment.
"We can confirm, however, that a large bang was heard around the aircraft and the terminal building."
He adds that the technician is undergoing treatment at a local emergency unit for his injuries."

I too hope he is OK

IFIX

13th Nov 2008, 22:31

To me it serves as a powerfull reminder to always use the self locking inflation adaptor.
If the wheel should let go, at least you will not be right next to it!

Hope he recovers.

ballyctid

14th Nov 2008, 06:08

Sir George.

For those who know Storm guys at MAN, it wasn't one of them, the person was indeed identified as a German national who had come to MAN to repair a tech Lufthansa CRJ aircraft, horrific incident and as an engineer who worked at MAN for many years and inflated many a tyre, i truly hope the guy makes a as full a recovery as possible.

chuks

14th Nov 2008, 08:08

When I was working in Miami there was an incident in Hialeah (a suburb near the airport that had a lot of shops doing support work).

Someone got it wrong and inflated the tire of a tire/wheel assembly to 10 times the correct pressure, according to rumour. Anyway, the damned thing must have been tight like a banjo string because as it was being transported it exploded in the back of the white van and ripped the vehicle apart. The driver was lucky to get away with just being deafened instead of being killed.

This is just another reminder to stay away from the sides of high-pressure tires when possible. Of course we usually end up crawling around right next to them on a pre-flight when that is not a good idea!

ShyTorque

14th Nov 2008, 08:28

Terribly sad news.

Someone mentioned a comparison between the use of nitrogen and oxygen to inflate a tyre. The comparison should only be made between AIR and nitrogen. The use of oxygen for this purpose is highly likely to cause a chemical explosion.

I recall a tragic case at a caravan dealer (next to Blackbushe airport) where two young mechanics used a welding O2 cylinder to inflate a tyre. The resulting explosion blew off the rim of the wheel, into the face of one of them, decapitating him.

The use of oil or grease anywhere near an oxygen cylinder outlet is also likely to cause a similar explosive effect.

Just wanted to clarify this as some of us do come into contact with bottled oxygen and the dangers (of what seems an essential gas for life) can't be overstated.

Doodlebug2

14th Nov 2008, 09:07

Had a tyre burst on a helicopter many years ago. One crew member had just been sitting on it, when someone noticed a bulge forming under his left knee on the tyre. A very rapid acrobatic manoeuvre kept him from bruising (or losing!) his wotsits. Massive bang, but luckily no other damage. Sympathy to ground mechanic injured.:sad:

Jofm5

14th Nov 2008, 09:09

MEN - Original article can be found here: Plane engineer maimed in blast - News - Manchester Evening News (http://www.manchestereveningnews.co.uk/news/s/1079662_plane_engineer_maimed_in_blast)

AN aircraft engineer lost part of a hand and part of a foot in a horrific explosion at Manchester Airport.

The Lufthansa engineer was carrying out an inspection of a 50-seater CRJ200 City Line plane at Terminal 1 when it is believed a tyre may have blown.

It is understood he also suffered slight face injuries and was treated by airport paramedics before being taken to Wythenshawe Hospital.

No aircraft was delayed or cancelled as a result of the accident and the airport remained fully operational throughout.

A Lufthansa spokesman said: "We can confirm a Lufthansa City Line engineer was seriously injured at Manchester Airport while working on an aircraft parked at a remote stand.

"We understand a loud bang was heard around the aircraft. The emergency services were called and the engineer was treated on site before being taken to hospital for further treatment.

"Lufthansa is working closely with the relevant authorities to establish the cause of the accident."

The aircraft flew in on Wednesday from Hamburg and was subsequently grounded following `technical issues'.

The spokesman added: "A Lufthansa City Line engineer was flown in from Germany to inspect the aircraft and make the necessary repairs to allow the aircraft to be flown back to Hamburg without passengers for a full repair."

Lufthansa City Line is a subsidiary of Lufthansa German Airlines and part of the Lufthansa Regional group of airlines.

The man was working alone and investigators were waiting to interview him to establish exactly what happened.

captainsmiffy

14th Nov 2008, 09:55

Horrified to hear the news; just wanted to clarify some info received many moons ago - 'during walkround, only ever approach the tyres from a fore/aft direction - never from the sides'. Just wanted to check that this is correct. Advice given to minimise self-damage if a tyre blew during walkround. Have I got this bit of wisdom correct? Have been meaning to ask but this thread brought it to the fore.

Mr.Brown

14th Nov 2008, 10:17

'during walkround, only ever approach the tyres from a fore/aft direction - never from the sides'.

That is the correct way at least for an unproven wheel assembly; Although with the wheel actually installed on the aircraft the likelyhood of the hub seperating is very slim; put certainly for inflating a tyre not installed that is the only place to stand. and the self locking inflation adaptor as mentioned earlier is the only way to ensure your out of the firing line!!!!!

MD11Engineer

14th Nov 2008, 10:18

Yes, it is normally not the tyre itself, that blows, but the metal rim (which is made up out of two halves, which are bolted together, with an O-ring between the halves), and the pieces will fly away sideways.
If the wheel rim tie bolts get damaged tdue to some reason, the only thing holding the two halves together will be the axle nut.

Nightfire

14th Nov 2008, 10:19

Well, it is correct that you should only approach a tyre from the front or rear, and not from the side. However, this applies mainly to maintenance (where I used to work in the military) - in case of a brake overheat, a suspected damaged wheel, locked brake, rejected T/O, etc.

As a pilot, when you do the walk-around, you usually have no other choice because some items to be checked (bolts, brake-assembly, pressure-transmitters, visible damage) will require you to walk around each bogie.

bcgallacher

14th Nov 2008, 10:22

Approaching wheels from front or rear is accepted practice which should be adhered to - especially on turnarounds where there is a risk of hot brakes.It might save you from tyre burst fragments and also from fusible overheat plugs blowing.

dixi188

14th Nov 2008, 11:10

Hope the guy recovers and gets some compensation.

If you wan't to see what happens to overheated wheels and brakes look at this on youtube. .Airbus A340-600 Rejected Take-Off test (subtitles) (http://uk.youtube.com/watch?v=hRzWp67PIMw)

I know this is extreme, but if we have hot brakes after landing I always leave the walkround for about 20 mins or so to be sure it's safe.

We had a smoking brake at Leipzig a couple of months ago on an A300. The fire services brought a fan to cool it down, but the guy got quite close to the wheel. His boss got him to move away.

After 40 years in aviation, some of the things I see on the ramp still scare me! It's the most dangerous place in civil aviation!

Safe flying and maintaining.

barit1

14th Nov 2008, 12:46

Ex Cargo Clown

14th Nov 2008, 13:05

Mere speculation -

There is the possibility that the cylinder was labeled N2, but was actually charged with O2. We had the reverse happen in a nursing home nearby, about 8 years ago, and several patients suffocated.

Very sad.

They should be threaded differently to stop this issue.

( And yes, I know about the Qantas incident)

Rob Courtney

14th Nov 2008, 14:37

Oxygen and Nitrogen are both right hand threads,(3/8BSP) you normally use left hand threads for fuel gas only (in an industrial application anyway, not sure about medical) An Oxy free Nitrogen cylinder is grey with a black top and white spot in the black, where as a Oxygen cylinder is Black with a white neck.

You shouldnt check cylinders by their colour anyway (it is just there as a guide) cylinders are ALWAYS identified by thier label. Cylinders are normally filled to either 230 or 300 bar depending on the supplier.

cockney steve

14th Nov 2008, 15:51

IIRC, Medical-gas cylinders have a square-section valve -body, with the outlet on the side....there are blind holes drilled near the outlet......the take-off connector clamps around the square-section but it's mating face will not seat, unless it has it's protruding pegs aligned correctly with the corresponding holes in the cylinder-valve. It needs determined abuse and modification to mate the wrong cylinder/manifold combination and get anything approaching a gas-tight joint.

Industrial cylinders often have different seating arrangements to foil wrongful connection...IE..."pub" CO2 cyl's have flat-face valve and a washer to seal.

others have bare-metal "cone" seals.....unfortunately, there are more gases than connector combinations . There is no easy answer, though the "medical" indexed peg-socket system seems pretty foolproof.

GAZIN

14th Nov 2008, 17:28

Very nasty, I wish the engineer well.
Obviously we don't know the circumstances of this accident, but it serves to remind us all of the dangers when working with aircraft wheels.
My employer now supplies all its wheels fully inflated, in order to save a few minutes during a wheel change! An insane policy in my view that puts engineers, stores personnel & shippers at unnecessary risk.:confused:

spannerhead

14th Nov 2008, 18:27

Mere speculation ?

Barit1

If anyone is speculating then it's you! I could go one better and speculate that the cylinder was filled with acetylene but I wouldn't want to suggest anything as ridiculous as you have.

A probable cause was that the cylinder regulator was set to high pressure normally used for the inflation of hydraulic accumulators and U/C oleo's (1800 psi or so). Such a small tyre as on the A/C involved would inflate to rupture point within a few seconds at this regulator pressure. I have never in my career heard of an incident like this that wasn't caused by anything but unfamiliarity by the operator with the equipment being used. Get well soon to the guy involved!

bizdev

14th Nov 2008, 18:53

MD11Engineer

14th Nov 2008, 19:23

Back in my spannering days - which was a while ago - Nitrogen rigs/hoses had right hand threads while oxygen rigs/hoses had left hand threads. I am not sure whether this was a BA convention or a UK convention because I do not think this distinction applied to Europe (at the time anyway).

No, in Germany we have a different system:
Flammable gases (with the exception of acetylene because of it's special dangers), like hydrogen or propane use lefthand male 3/4" threads.
Acetylene uses a clamp connection similar (but not the same) as UK medical cylinders.
Non-flammable gases use righthand 3/4" male threads, but oxygen uses righthand 5/8" male threads, while compressed air (e.g. for scuba equipment) uses righthand 5/8" female threads, so it is impossible unintentionally to e.g. hook up a nitrogen cylinder to an oxygen rig.
(all threads as seen on the cylinder valve).

I also assume that the engineer used a high pressure gauge to fill the tyre, instead of a low pressure one.

Nopax,thanx

14th Nov 2008, 19:36

GAZIN you can get this policy overturned. It is simply dangerous. I had a scare in a wheel shop a few years ago when unloading a 727 wheel from a truck. It bounced high in the air when we manhandled it onto the ground and we realised that it was still full pressure (180psi) It had good tread on the tyre and we wondered why it had been sent in. I checked one side, then the other, and found a twelve-inch section of rim had cracked off. :eek: We didn't used to check wheels on arrival at the shop for transport pressure (35psi) but after that, they were checked before getting them off the wagon.

Let your QA department know about this practice and get it stopped. Your NAA will back you on this.

barit1

14th Nov 2008, 20:01

spannerhead - I should have made it more clear that the speculation was indeed mine. Sorry for the confusion.

But whether it applies in the present case or not, the N2 vs O2 mixup HAS happened in the past, with tragic results.

Rob Courtney

14th Nov 2008, 20:12

In the UK both Oxygen and Nitrogen have the same right hand thread (as do all non flammable industrial gasses such as Argon etc) Its perfectly possible to use a Oxygen regulator on a Nitrogen cylinder and visa versa. Im not aware that OFN and Oxygen used in avation (with the exception of medical) is any different to standard industrial cylinders (although I stand to be corrected).

Acetylene in the UK uses a left hand thread, it only becomes dangerous when the cylinder is heated or suffers a significant impact.

MD11Engineer

14th Nov 2008, 21:04

My employer now supplies all its wheels fully inflated, in order to save a few minutes during a wheel change! An insane policy in my view that puts engineers, stores personnel & shippers at unnecessary risk.

We also have to prefill uninstalled wheels every day in the hangar, to always have a shipset ready on the line (at the other side of the airport), to be able to change a wheel if necessary during one of our very short turnarounds without causing a tech delay.
It took ages until the companywould buy us a screw-on filler adapter, which didn't need to be pressed against the valve by a mech standing right beside the wheel. Still no safety cage yet.

Krystal n chips

15th Nov 2008, 07:13

Another tragic accident....and some very uniformed comment as to the maintenance procedures with regard to tyre inflation.

As ever on this site, speculation with regard to the causal factors is rife.

So, let's try and take a more realistic overview of the possible causes shall we.

From the information so far, it can be assumed the aircraft was not on a T/R and therefore the tyre px would be cold and were being recorded as part of an A/F. Possibly they were within the min / max px values but towards the lower end and therefore needed to be adjusted as there would be no other reason to inflate an in-situ tyre. So far, so routine..unless the wheel was being changed for whatever reason...ie a new bay serviced item was being fitted to the a/c in which case it would need to be inflated from storage and / or transportation px ....thus it would be a new assembly and would / should have been subjected to a rigourous testing and inspection procedure anyway ..and at this point we simply do not know the circumstances applicable, the point being that both scenarios offer different possibilities as to why the incident occurred.

Tyres however, do not simply "let go" at random. So far, nobody has mentiond the possible condition of the tyre....such as any one of the following:

Embedded object
Deep cut
Bulge
Tread seperation

To name but four possible other contributory factors.

The classical and invariably tragic bar / psi confusion has been mentioned of
course as has the possibility of a failure of the retaining bolts or hub.

As for a cage on a Line station, maybe, maybe not depending on the operator....however....it would be highly unlikely that even with a cage, for routine adjustment of tyre px, the wheel assy, would be removed, placed in a cage, inflated, and then re-fitted given that the adjustment px is only ever going to be a small value. Inflation from transportation / storage is another matter however.

G-SCAW....whatever you do for a living, one thing's for certain, you are not an engineer !...but thank you for your first paragraph in Post 5....most "entertaining"....:mad:...and for your info, oxygen bottles are usually charged to around 1800psi on an aircraft.

Along with everybody else, I wish the individual concerned a full recovery....however...and has invariably been the case within aviation, the incident offers yet another safety awareness exemplification with regard to procedures and practices and from my perspective, a more than valid one.

The official report on the incident will therefore make interesting reading.

chuks

15th Nov 2008, 07:43

In a previous life I worked as an aircraft mechanic/line maintenance supervisor in the U.S. Army...

The pros know all this stuff but amateurs are allowed to play with the tires on the airplane so:

You should deflate a tire before taking it off the axle and especially before undoing the two halves of the wheel. (This one seems so obvious but people still ignore the warnings cast right into the wheel halves and kill themselves.)

You shouldn't bang in the pressure until a dry tire bead seats itself with a bang but use some sort of (non-oily) lubricant. That bead seating in that way can cause a wheel to explode if it has a flaw and if that is your hand holding the inflation chuck...

Just cracking the valve on a high-pressure cylinder will still put full pressure into a tire because of that boring old law that says that pressure in a confined system is equal at all points in the system. (We used to lose guys to this one all the time, too idle to go find a regulator for tire inflation.)

I also had to deal there with split-rim truck tires, big 20-inch ones.

The killer with those was the locking ring coming loose after a tire change, when we were supposed to use a cage which was usually not available! I would see guys bent over inflating those things when that ring can take your head off, or so I was warned.

Basically, tires are best left to the pros to deal with since they can be surprisingly dangerous even to trained personnel, as this accident shows. An amateur can find several ways of at least causing serious damage if not personal injury just trying to save a bit of money. I know enough to just leave them alone, not having the equipment to deal with them safely.

MD11Engineer

15th Nov 2008, 09:34

As for a cage on a Line station, maybe, maybe not depending on the operator....however....it would be highly unlikely that even with a cage, for routine adjustment of tyre px, the wheel assy, would be removed, placed in a cage, inflated, and then re-fitted given that the adjustment px is only ever going to be a small value. Inflation from transportation / storage is another matter however.

This is exactly what I was talking about. Pre-inflating new, uninstalled wheels from transport pressure (appr. 30 PSI) to full operational pressure (200 PSI) so that a set of wheels can be kept on the line to allow for fast wheel change on short turnarounds without loosing time for inflating it from storage pressure.
Ok, the wheels have been inspected in the shop, but mistakes are always possible.
Also, I noticed that manyengineers / mechanics don't deflate the wheels before removal. They usually give two reasons: Either that it takes too much time or that the noise of the escaping gas is too loud for them.

Mac the Knife

15th Nov 2008, 09:52

Tyre blows are NOT nice. Did a boy the other week where a truck tyre let go in his face.

Lost one eye, badly damaged the other, comminuted LeFort III facial fractures.

Took a while to reassemble that one.....

Mac

PeePeerune

15th Nov 2008, 11:48

md11engineer...

I noticed that manyengineers / mechanics don't deflate the wheels before removal. They usually give two reasons: Either that it takes too much time or that the noise of the escaping gas is too loud for them.

so what do you recommend if you are replacing a brake unit????????

spannerhead

15th Nov 2008, 12:47

The A320 AMM gives you the go ahead not to deflate the tyre before wheel removal if it is going to be refitted. This working practice maybe against convention but it does save a whole lot of time.

On a lighter note, many years ago a young apprentice was told to use the cage for the first inflation of a tyre after the wheel was assembled. 2 minutes later the apprentice was inside the cage with the wheel on the outside! No it wasn't me!!

MD11Engineer

15th Nov 2008, 13:00

md11engineer...

:
I noticed that manyengineers / mechanics don't deflate the wheels before removal. They usually give two reasons: Either that it takes too much time or that the noise of the escaping gas is too loud for them.

so what do you recommend if you are replacing a brake unit????????

What I've learned during my apprenticeship was to at least reduce the pressure (in jacked up condition, not with the aircraft weight resting on the tyre) to appr. storage level and to inflate it again afterwards to full operating pressure. I know, this is the theory and it takes time. And time is money.
Using a pneumatic-hydraulic jack, which is powered by nitrogen from the tyre also helps

Krystal n chips

15th Nov 2008, 13:28

This might help and offer some very professional clarification for those who are interested....and probably prove equally "invaluable" for the "never been near an aircraft in their lives"..brigade of "experts".

Dunlop Aircraft Tyres Limited - Tech Support (http://www.dunlopatl.co.uk/tech_support/index.aspx)

As yet though, we still do not know why the engineer was working on the wheel concerned.....and until we do, then apart from stating the basic safety requirements and maintenance procedures, everything else is pure hypothesis is it not?.

A seemingly daft question however.....will this be the subject of an AAIB or HSE investigation....or both ?.

sexpest

15th Nov 2008, 15:34

A lot of speculation going on here chaps. No mention yet by anyone of a Nitrogen rig problem i.e incorrect regulator or regulator fault possibly putting 3000 psi straight into the tyre, if that was the case then the poor guy had no chance.

PeePeerune

15th Nov 2008, 16:31

What I've learned during my apprenticeship was to at least reduce the pressure (in jacked up condition, not with the aircraft weight resting on the tyre) to appr. storage level and to inflate it again afterwards to full operating pressure. I know, this is the theory and it takes time. And time is money.
Using a pneumatic-hydraulic jack, which is powered by nitrogen from the tyre also helps

even nominal pressure in a wheel would cause serious damage/injury.

MD11Engineer

15th Nov 2008, 16:44

Ok, but you'd remove a lot of the stored energy. From 200 PSI down to 50 PSI makes a lot of difference.

As a reminder the universal gas equation:
p*V= N*R*T
p=Pressure
V=Volume
n=Number of moles of gas
R=Universal gas constant
T=Temperature
p*V is the potential energy stored in the gas
Reducing the pressure by 75% also reduces the stored energy by the same amount.

boeing_eng

15th Nov 2008, 16:50

Sexpest(!)....You obviously didn't take the time to read post #8 by me two days ago:ugh:.....Quote:

"Many incidents similar to this in the past have been caused by the use of faulty charging regulators (or no regulator at all!) Charging in Bar's instead of PSI has also caused some accidents"

Some utter tosh being posted as usual by people who clearly have never been near a live airliner in their lives!

Please leave the uniformed speculation out.....Yes, there will be a full HSE investigation without a doubt!

MD11Engineer

15th Nov 2008, 17:22

Sexpest(!)....You obviously didn't take the time to read post #8 by me two days ago.....Quote:

"Many incidents similar to this in the past have been caused by the use of faulty charging regulators (or no regulator at all!) Charging in Bar's instead of PSI has also caused some accidents"

Some utter tosh being posted as usual by people who clearly have never been near a live airliner in their lives!

Please leave the uniformed speculation out.....Yes, there will be a full HSE investigation without a doubt!

Ok, the facts we know is that an engineer got badly injured when a wheel (from what we know installed on an aircraft) exploded, while he was working on it.

Now we had a discussion about possible causes.
It might have been:
1) a faulty rim or tyre
2) a defective filling gauge
3) the wrong type of pressure regulator (high pressure for filling struts instead of a low pressure one for filling tyres, don't laugh, I've seen this happen) or no pressure regulator at all.

We discussed the sense or nonsense of deflating a wheel before removing it (IMO necessary, I have seen damaged wheel ties bolts).
We also discussed the practice of fully inflating uninstalled wheels on line stations without the proper safety equipment.

What I think can be discounted is the idea of somebody having confused oxygen and nitrogen cylinders.
(though it surprised me to learn that in the UK the connectors for nitrogen and oxygen cylinders are the same. This explains the reaction of our airline QA, when a nitrogen cylinder was found (though not connected to it) on an oxygen rig at an UK station a few months ago).

I've been working in aircraft maintenance now for more than a dozen years (mostly line maintenance, during which I must have changed hundreds of wheels and brakes) and I AM a licenced engineer with three transport category aircraft type ratings. I have also seen shortcuts taken by engineers and mechanics either out of convenience, because equipment was not available or as not to loose time. I have to confess that occasionally I was guilty of this as well, not involving the airworthiness of the aircraft, but breaking health and safety rules, risking my own health or life.

Concerning tyre explosions, a few years ago, while driving to work, I witnessed the explosion of a lorry tyre on an Autobahn (I was driving about 50 meters behind the lorry). A BMW, which was right beside the exploding tyre, had it's R/H rear fender and rear bumper torn off. Since then I'm a bit carefull concerning wheels and tyres.

sexpest

15th Nov 2008, 17:25

Apologies boeing eng, missed that one! couldn't agree more, a lot of very uninformed speculation going on. As you say the in the fullness of time exactly what happened will come to life and hopefully lessons will be learnt.

boeing_eng

15th Nov 2008, 18:16

MD11 Eng....I don't think anyone is questioning your credentials:}

I think it’s fair to say the cause of this accident will have been mentioned somewhere in this thread by now!

Those of us involved in line maintenance should know the risks of working with wheels and the correct procedures to follow (all this talk of deflating a wheel before removing it is pure egg-sucking!!) There are obviously variations between companies but some comments/observations that have been made are frankly ridiculous!

Let this poor Guy make his hopefully good recovery and then await the findings of the Enquiry.

Continuous Ignition

15th Nov 2008, 18:55

This nearly happened to me. Servicing a low tire on a B737-700. Had pressure cranked up and servicing adaptor on hose. Did a double check to make sure I had close to the required 200psi dialed in to ensure a positive flow. That is when I realized someone had swapped the low pressure regulator with a high pressure one and had it set up for tire servcing. I had nearly 1800 psi dialed up for the serivce...

Informed Management and their attitude was "oh well"

Not the response I expected from two seconds from being blown to bits. Needless to say I was NOT a happy camper but no one would own up to the swapped regulator.

magpienja

15th Nov 2008, 19:41

Very dangerous things inflated tyres, if a heavy truck is passing me on the motorway I always wind the window up just in case,

Would prob blow the window in but you can only try.

Nick.

AndrewMcN

15th Nov 2008, 20:18

There is an alternative way of inflating Aircraft Tyres.

The equipment we supply stores Liquid Nitrogen at 350 psi and then converts it to gas, at room temperature, then supplies it to the Tyre through standard hose end fittings. This means that it is impossible to provide gas at a pressure greater than 350 psi which is too low to cause rupture of the Tyre. By law aircraft tyres must have a min burst pressure of 4 times their operating pressure so this system is much safer.

The tank holds the equivalent of 20 cylinders of gas and is filled once a week by BOC. There is therefore no cylinder handling or reconnection, also no empty or full cylinders have to be transported.

Visit | McNaughton Dynamics UK | Nitrogen, Oxygen and Cryogenic Pressurisation Servicing Units | (http://www.mcnaughton.co.uk) for further information.

dontdoit

16th Nov 2008, 07:40

A wound up window will provide no more protection than holding up a sheet of A4 paper when the tyre blows.

PeePeerune

16th Nov 2008, 09:29

md11

Concerning tyre explosions, a few years ago, while driving to work, I witnessed the explosion of a lorry tyre on an Autobahn (I was driving about 50 meters behind the lorry). A BMW, which was right beside the exploding tyre, had it's R/H rear fender and rear bumper torn off. Since then I'm a bit carefull concerning wheels and tyres.

what would have been the pressure in a lorry tyre then??? . as you stated in your own post a lot of damage was done to the car beside it.

because of such a large volume in a large main/nose wheel there will always be a risk of serious damage even at low storage psi (50).

HotDog

16th Nov 2008, 09:40

http://i106.photobucket.com/albums/m246/adamtakach/Crackedmainwheel.jpg

Found on my preflight walkaround after aircraft certified serviceable.

pilotmike

16th Nov 2008, 10:10

if a heavy truck is passing me on the motorway I always wind the window up just in case,

If one is worried about an exploding lorry tyre, why choose to add broken glass as well as shredded rubber as potentially lethal projectiles?

magpienja

16th Nov 2008, 20:06

Why do I wind the window up, well as far as I know side windows on cars are toughened so no big lumps of glass to cut the jugular, saying that you can only try to protect yourself with whatever you have,

To who ever asked about big truck tyres and inflation pressures, it about 120psi.

Nick.

ozaub

17th Nov 2008, 00:00

Reverting to the need for nitrogen inflation please, and just a little off thread. Tyre rubber compounds break down over time and emit volatile flammable compounds. If tyre is inflated with air the internal mixture is potentially explosive, hence the need to use inert nitrogen.

If I remember correctly nitrogen inflation only became mandatory as a result of accident to Mexicana B727 in March 1986. Details at http://aviation-safety.net/database/record.php?id=19860331-1&lang=en (http://aviation-safety.net/database/record.php?id=19860331-1&lang=en). Airlines did not willingly embrace the change!

Terry McCassey

17th Nov 2008, 01:55

HotDog - Doubt you found that on your preflight walkaround, that's on the inside looking out, hidden by the brake heatpack

HotDog

17th Nov 2008, 02:41

No it is not Terry. I took the picture after I made them change the wheel.

(FYI LAME and Flight Engineer, 45 years worth.) Cheers, HD.

HotDog

17th Nov 2008, 02:54

http://i106.photobucket.com/albums/m246/adamtakach/Tyreburst.jpg

Another one for you Terry, this one was easier to spot.:E

Litebulbs

17th Nov 2008, 03:07

Is that you hotdog, or someone you got to do it?

Litebulbs

17th Nov 2008, 03:18

Sorry.

An engineer has been seriously injured and I apologise for getting into a slanging match.

vs69

17th Nov 2008, 03:21

Well spotted Hotdog,... but without wanting to pick a fight that pic is the inboard half of the wheel as Terry stated, you can see the splines where it engages on the brake rotors. Good pic tho!

SMOC

17th Nov 2008, 03:26

No it is not Terry. I took the picture after I made them change the wheel.

That is a pic of the inside though, as it has the heat shields and tangs that the brake discs slide onto.

HAWK21M

17th Nov 2008, 06:15

Normally in such cases....Its the lack of a pressure regulator used while Tire servicing.
Non deflation of the tire prior to removal.
Excessive serviced.

Sad event.....

regds
MEL

HotDog

17th Nov 2008, 07:36

Sorry vs69, SMOC et al. The picture is as I saw it on my walkaround. It is the No. 12 body gear wheel on a 747F-200 in Manchester. As I was the chief check and training flight engineer on the fleet, I used this picture in a notice to F/Es to keep their eyes open. If you have access to a B747-200 Maintenance Manual, have a look at 35-45-00. The picture is of the outboard wheel half.

Fargoo

17th Nov 2008, 10:22

Inboard or outboard, i'm surprised the wheel was clean enough to see the cracks.
All ours are usually covered in a layer of sooty black brake dust.

Either way it was a good spot as a lot of crews tend to focus on the tyres on their walkround.

cockney steve

17th Nov 2008, 10:51

re-Commercial vehicle tyres.....they're designed for lower speed,poorer surface,much more load-variation and long cycles,

Thick tread and sidewalls (curb impact is an everyday occurence) heavy carcass construction.....they are not designed to smack onto a road with a speed differential of~150 mph, though!:}

when a commercial tyre blows, the chunks are probably bigger and heavier, pro -rata, compared with Aviation tyres.

Av. tyres appear to be of substantially larger cross-section,therefore, given the higher inflation pressure,I'd suggest:-

close in, both types are lethal if they let go........Av tyres the danger diminishes much more rapidly with distance (see the fire video) as the weight and energy is lower in the "shrapnel" compared with a road-tyre..

Safety inspector for my compressor reservoir had many a tale about tyres and deceased ex-customers.

AndrewMcN

17th Nov 2008, 14:51

Hi Ozaub,

You are absolutely correct. A dragging brake caused that accident and the gas involved was Isoprene, which is given off by rubber when it gets hot. Isoprene is highly explosive in the presence of compressed air and in the Mexicana flight, the exploding tyre fractured the hydraulic lines in the wheel well, causing the accident.

Nitrogen is also used in struts and accumulators to prevent Dieseling that would occur between the hydraulic oil and any compressed air previously used.

United B-777

17th Nov 2008, 15:34

What a horrible accident! I hope the engineer gets well soon!
Does anybody have any hint as to where I could find out who he was? I did two internships at Lufthansa CityLine-Technik in Hamburg and am kind of afraid that it was one of the people I know. Not that that would make it any worse, I would just still like to know... On the other hand I'm not sure if it is the right gesture to call CLH-Technik and ask...

Thanks for any advice.

All the best and fly safe!

-Jakob

liccy1

17th Nov 2008, 18:15

Have to agree with Terry. I find it difficult to understand how the picture shown of the cracked wheel could have been visable on a pre-flight. The picture is of the I/B side, the brake pack covers this area completely. (unless the outer split sheel was cracked also)
I hope the injured engineer gets well soon.

HotDog

17th Nov 2008, 21:38

http://i106.photobucket.com/albums/m246/adamtakach/Image0001-3-1.jpg

Correction, you are right it is the inner hub, with a 360 deg. circumferential crack. Inner hub cracks were visible through outer hub spoke holes. It happened a long time ago in October 1993. I just dug out my records to refresh my memory. Cheers, HD.

Date: 6th October, 1993
From: C.F.E.T. TO: All Aircrew
Subj : Wheel inspections

The attached illustration shows the #12 main wheel (right rear body gear) removed from ****** at ********** recently.

It is very unlikely that the damage to this wheel occured during the last landing. This highlights the necessity to carry out a thorough inspection of all wheels during walkaround checks. Although several broken wheel tie bolts have been discovered by our crews during walkaround inspections on *** airplanes in the past, damage of this type could easily be missed by a cursory inspection.

The potential consequences of this wheel disintegrating need no elaboration.

Regards,

*************
*************
Chief Flight Engineer, Training.

Rainboe

18th Nov 2008, 16:10

Can one of you tyre experts say what is the best way for checking tyre pressure for pilot walkarounds as in seeing if a tyre is deflated? Thinking in terms of medium jet tyres. Widebody tyres just seem rock hard whatever their pressure.

whatbolt

18th Nov 2008, 16:29

Yeh, you kick it fairly hard and listen to the sound it makes, if they all sound the same there all about the same px - what you cant tell is if thats low or high unless the profile of the tyre looks different at the bottom.

Rainboe

18th Nov 2008, 16:32

So the back of a 2 or 3 cell Maglite is just right for the 'reverberation' test? Shame I have just gone onto a LED torch the size of a little finger.

Krystal n chips

18th Nov 2008, 17:00

The best advice I can offer is to think of a car tyre..ie, if it looks "flat" or appears to be bulging slightly at the side wall, near to the area of tyre in contact with the ground (footprint), there is a reasonably good chance it is low on px...try doing a quick comparison check with the footprint of the other three as a guide......or simply ask an engineer (nicely!) to check it for you.

White Knight

18th Nov 2008, 17:10

All very complicated.... Just check the wheel page on the ECAM for the TPIS:}

vs69

18th Nov 2008, 18:51

So you will be able to audibly tell the difference between tyre pressures over the air-con packs??? If it does look flatter than normal on the bottom ask the engineers to jack it and spin it so the rounder bit is on the bottom,hey presto!

Before this thread goes off on too much of a tangent is there any more news about the eng involved and what REALLY happened? Get well soon old chap.....

Micky

18th Nov 2008, 19:07

Last I heard is that he is not in al life threatening condition any more. Probably can be transported back home at the weekend. Sad news is that he lost part of foot and arm which could not be saved. Very sad story!

As to the course of the incident. No further information is available.
The AAIB and the airline are investigating.

Hope he recovers quickly

Micky

ARINC

18th Nov 2008, 22:30

210 Psi 15 Bar on the A380

Both temperature and pressure on the ECAM no guesswork on the walk round. They also have a handy colour coding on the ECAM tyre page. Green, Amber and yes you guessed it Red.

greuzi

19th Nov 2008, 00:47

Strange thread this one.
Many thoughts of O2 vs. N2. Bar vs. PSI. I would guess neither are relevant here.

Getting back to basics, if the guy was certified he would know the basics?

The advice to always approach from front or rear is life saving. Some have mentioned, but if nothing is being done to the wheel/tyre it will sit there happy all day and night. I was always told treat it like a woman.. In front or behind work well ...but beside has the potential to ruin you. That's complete rubbish of course but you will all remember next time so I figure it's good advice.

I have not read the thread completely, but the poor guy was at the tyre because of a reported issue?

Have witnessed two tyres explode. Both on a car so we are not talking 200 psi. Mine happened after two new brand new (top branded) tyres were fitted. Drove up the A1. After a few roundabouts the steering was heavy. Stopped at the next service station and the nearside tyre measured 12 psi. Did the normal (stupid) thing and put a bit of air in. I reiterate....a bit! Way before 16 psi on the guage the thing blew up. Hot in there?

My knowledge of physics is just A-level but if the air (gas) in the tyre was very hot then the little air I added, expanded rapidly. Very rapidly on a carcass with weakened sidewalls due to the low pressure flexing for a few miles?

I didn't learn. I thought a fluke and went to the other front tyre. This time much much more gentle....still scared....but...BANG! at 14 psi.

Have never had any issues with tyres ever since but will never forget that trip up the A1.

Speedy recovery to the man concerned. Is not why we spend our time around aeroplanes.

sdh2903

19th Nov 2008, 07:39

All these comments about kicking tyres, hitting with torch, Ha what a load of rubbish. :rolleyes:

Any medium size jet wheels can have a substantial pressure drop or be over inflated before becoming visibly different to the naked eye or by listening to the sound it makes!:ugh:

It might be a reasonably effective method on a car but on an Aircraft, a calibrated tyre pressure gauge every time, TPIS is ok for a quick check but even that has to be cross verified with a gauge fairly often.

Back to the topic, Wish the guy the best of recoveries back home.

matkat

19th Nov 2008, 07:48

Anyone remember the nationair DC-8 crash in Jeddah a few years back caused by an under inflated tyre exploding in the wheel well after it had taxied approx 5 miles then took off? I can not remember the % of under inflation but it was large however visually no difference could be seen between the low tyre and others the only way to check is with a gauge or EICAS, if you are lucky enough to have one.

brakedwell

19th Nov 2008, 09:37

Surely the majority of this thread should be renamed something like: Working with Tyres and transferred to Tech Log.

Best wishes to the LH engineer and I hope he recovers soon.

angels

19th Nov 2008, 09:45

Micky - Thanks very much for the update on the engineer.

I was thinking he'd rather been forgotten about.

Get better soon, whoever you are mate.

scrivenger

19th Nov 2008, 10:06

Absoloutley agree with the last two posters. Thanks for the update Micky. And yes get better soon, terrible thing accidents.

whatbolt

19th Nov 2008, 12:24

Au contre old chap, these ARB desert tips have been around for a while - some engs can tell by the sound and some cant. Dont put all of us in one bag.

SVR

19th Nov 2008, 12:34

Believe a Caledonian/BUA VC10 had a similar event - early seventies? - on one of the S/America routes - tyre burst in u/c bay some minutes into the climb, thought initially to be an explosive device, considerable damage but fortunately the crew nursed it down safely.

cockney steve

19th Nov 2008, 13:38

The only worthwhile visual info. you'll get off a low-pressure tyre is likely to be below 15 PSI in the case of a car, it's nearer 6 psi.........anything over and the tyre LOOKS normal......a gauge is the ONLY way to check pressure accurately...a pilot's walkround is, by the nature of things, fairly superficial (was going to say cursory) Any tyre appearing to be "flat" is probably already weakened by the landings /takeoffs since it lost pressure.

IMO, delay the flight, change the wheel/tyre assy.......then the Engineers can load-test it at their leisure in a cage.

The victim of this sad incident will now be severely hampered in his efforts to make a living. glad to hear he's on the long road back to recovery.

smudgethecat

19th Nov 2008, 13:44

Here here, however one would hope a company such as LH will be able to sort him out with a postion that doesnt require 100 per cent fitness ,QA, tech services etc

spannerhead

19th Nov 2008, 18:16

etc......B2

Micky

19th Nov 2008, 18:16

The victim of this sad incident will now be severely hampered in his efforts to make a living. glad to hear he's on the long road back to recovery.

Good evening
CLH and "Stiftung Mayday" are working close together to help not only him but also the family. As well as all employees, are gathering money to help him and his family. It is a very sad incident and we are all deeply moved.

Micky

shane 1962

21st Nov 2008, 11:50

I am an ex CRJ-200 engineer and i can tell you that the nose tyres are very small and thus hold a small volume of N2. If you were to try and top-up these tyres with a regulated source of gas that was too high you will quickly be in trouble especially if there was some defect with the tyre.
Apologies if this has already been covered in this thread.

Terry McCassey

23rd Nov 2008, 08:59

HotDog

Your guarded apology in your post 79 is accepted with grace, the patronising comments in posts 66 and 67 I take with a degree of unease. Flight Engineers do not tell Ground Engineers what to do. In this case the call was right but in the case of doubtful wear limits, the MM is the arbiter, and ultimately, it's the Captain's call. I have on several occasions had cause to question a walkaround call and asked the F/E to log it when he gets upstairs. I will then inspect, and if need be sign off per mm 32-45-00 and let the Captain decide. BTW, I have 38 years Line experience as a Licensed Engineer, many of which have been spent on B742/3, I am still unsure if I could have seen the cracks on the inner hub through the cooling holes as most of the inservice hubs I see are black with brake dust. It is my experience that Ground Engineers do not want to fight the Flight Engineers, the common goal is to offer a safe and airworthy aircraft for service. Tyre are nasty things and as can be seen in this post, and can bite without warning.

I really do hope this guy makes a speedy recovery and my thoughts are with him and his family, there but for the grace of God go I . . .

NutLoose

23rd Nov 2008, 14:12

Glad he is recovering,

I remember a VC10 taxying out where the rim dropped of the mainwheel, was a lot of discussion how to deflate it safetly, in the end and what I thought was stupidly they got the last person to work on it in the bay to go in screw a deflator into the valve then run out sharpish, it went down without coming off.... They came up with a hundred and one stupid ideas along the way BTW.

NWT

12th Dec 2008, 07:01

Getting back on thread....is there any further news about exactly what happened?

g4phil

8th Jan 2009, 07:09

Does any one have any information on the engineer injured?

Best wishes to him and his family for the New Year.

subsonic69

8th Jan 2009, 10:46

I hope the lad recovers asap, and i hope that this serves as another wake up call to the things we normally take for granted since it seems to be a habit / or a regular practice of replacing wheels in which we don't even try to release the pressure even a bit.

Regarding Sir Terry's comment on letting the Captain decide on wether to fly the aircraft or not. I have to disagree on this one. It is right that you have to refer to the AMM ALWAYS! But, signing a release for an aircraft with that kind of damage on the wheel and letting the Captain decide is never and will never be a good decision.. I hope you don't take this personal sir. I just believe that we have a job to do and we have to do the job accordingly. :ok:

We can always make things safer if we want to.

Terry McCassey

9th Jan 2009, 07:23

subsonic -With the example of the damaged wheel in this thread, in no way of course is the serviceability in question. The wheel and it's mate has to be changed as well as a full inspection of the brakes, truck etc, only then of course can it be offered for service. The point I am making is that in our job, I can offer an aircraft for service and occasionally there will be disagreement with the captain. It is the captain who has the last word as to whether he will take it or not, his and his alone. If he is not comfortable with an MEL for example then he ultimately takes responsibility as to if it goes or not, not me. What I was trying to illustrate, maybe not too well, is the " I told him to change it " remark from the F/E I find confrontational. If the wheel has broken into a zillion pieces then of course I'll change it. My personal working relationship with F/E's over the years has generally been good and I think between us we can get the job done ! Hope this explains it . . .

AndrewMcN

9th Jan 2009, 08:33

Is there available a preliminary report to this accident similar to the one issued for the exploding Oxygen Cylinder on the Qantas a/c.

This is such an important issue with so many personnel worldwide performing the same task daily.

subsonic69

9th Jan 2009, 13:17

..then if that is the case sir then i would agree... it is true that sometimes the captain might ask for another aircraft if he decides not to fly the aircraft that we just signed for release. my apologies also if i misunderstood your point in your post sir..

:O

and regarding the Qantas diversion to Manila try this linik --> http://www.flightglobal.com/articles/2008/09/02/315377/investigators-release-preliminary-report-on-qantas-explosion.html

tonytech2

12th Jan 2009, 17:56

In a discussion with a Captain who wished to take an aircraft with an open fault, I informed him that whereas I could not make him take an aircraft (Captain's right of refusal) , he could not take one away from me until I released it (my airworthiness release as a licensed mechanic) Works both ways.

Tire explosions are ugly things - I inspected the wheel well of a B727-200 after it was partially repaired having suffered a tire explosion in Havana. We finished the repairs which were extensive. It looked like a bomb had gone off there and had the aircraft been in flight it would have gone down. Had personnel been in the area they would have been killed. The same airline had another one a bit later that that led to the Airworthiness Directive against using compressed air in braked wheels.

I have seen results of wheel explosions over my fifty plus years of maintenance. Several were due to using unregulated or high pressure regulators for filling tires. Early on in my career, a GSE person lost a lower jaw filling a bag cart tire directly off an 1800 psi bottle. Lack of thought does it too. A Constellation brake accumulator exploded when a mechanic went to lunch leaving a bootstrap compressor running to charge the accumulator. No one injured there thankfully. We can be our own worst enemies.

One airline developed a spiked chock for deflating tires that were dangerously hot or actually afire or had cracked or pieces of rim broken out. You placed it against the tire like a chock (approaching from the tread side of the tire) and used a tug to shove it up against the hollow spike. It would pierce the tire and deflate it. Quite effective and keeps you away from the side of the wheel where the danger is. Be worthwhile having one available and probably something the fire service people should have too.

Raikum

11th Oct 2010, 10:23

The AAIB have published the final report on this dreadful accident here http://www.aaib.gov.uk/cms_resources.cfm?file=/Bombardier%20CL600-2B19%20CRJ200,%20D-ACHA%2009-10.pdf.

AndrewMcN

11th Oct 2010, 15:22

Thanks for providing this link, the report is fascinating.

Sounded like an accident waiting to happen.

Alber Ratman

12th Oct 2010, 20:18

if the technician had purged the line, he would have noticed that the pressure was a bit high from the regulator to inflate a cover!!

1500 PSI from a line tends to be noticed!

I'll get my coat..:E

Krystal n chips

13th Oct 2010, 05:25

Thanks for the link.....:ok:

From my perspective, there's enough training points in there to educate the baby engs I train very comprehensively.

On the other hand, and from a different life, strange that a LH eng should make such a series of errors...those I worked with / met were always very competent guys.

forget

13th Oct 2010, 09:49

tonytech2's post -

One airline developed a spiked chock for deflating tires that were dangerously hot or actually on fire or had cracked or pieces of rim broken out. You placed it against the tire like a chock (approaching from the tread side of the tire) and used a tug to shove it up against the hollow spike. It would pierce the tire and deflate it. Quite effective and keeps you away from the side of the wheel where the danger is. Be worthwhile having one available and probably something the fire service people should have too.

Makes good sense to me. Any else use this?

Bumpfoh

13th Oct 2010, 10:40

210 Psi 15 Bar on the A380

Not wiily waving but the 380 I work on is 219-229 PSI on the mains as per the AMM. (Bridgestones)

Not sure if different tyre make changes the px?:ok:

Alber Ratman

13th Oct 2010, 22:19

Driving a spike into an inflated tyre is a very dangerous proposition. The effects could end up in a blow out. If a wheel is suffering hot brakes / fire, then having fuseible plugs fitted is the only safe design feature. Trouble is they can go with Nigels using excessive braking on taxi etc. Damaged wheel? Fit a tyre deflator plug and retire sharpish..

Beeline

14th Oct 2010, 16:51

Mines smaller but it's what you do with it!

A321 225psi on mains!!

Tire deflator every time,

Thoughts are still with the guys family, be careful out there

Krystal n chips

15th Oct 2010, 03:59

I seem to recall Lightning tyre px was around the 200 psi mark....a lot smaller and just as potentially lethal.....if you choose to abuse common sense and safety procedures.

As for the spike in a wheel, ok, does anybody have any photographs / vid evidence of this procedure at all ?.....personally, I would be happy to watch a demo....from behind a blast wall several hundred yards away.

I don't doubt the feasibility of the process for one minute....only the practical application which seems to contradict everything I have ever been taught about tyres.....always willing to learn however so I look forward to being educated.

forget

15th Oct 2010, 08:40

As for the spike in a wheel,

I think we have different types of spike in mind. I was thinking of a giant, very sharp, hypodermic needle. Small orifice so pressure is released over a minute or so. As tonytech said, it goes in through the tread, not the side wall. I can see this working without any risk.

AndrewMcN

15th Oct 2010, 10:17

Talking about aircraft tyre pressures, is there a central data base or listing showing the different pressures used for different aircraft? When inflating car tyres, there used to be a wall chart showing the pressures for most cars, the aircraft version of this is what I am looking for.

Any suggestions?

forget

15th Oct 2010, 10:42

Tyre pressure chart. Heavie's mains here -

http://www.aci.aero/aci/ACIAPAC/Download_Files/tyre%20pressure%20survey%202009%20cover%20letter.pdf

Tyre sizes here -

Desser Aircraft Tire & Rubber Company (http://www.desser.com/pressurechart.php)

Excellent manual from Goodyear.

http://www.goodyearaviation.com/resources/pdf/aircraftmanual.pdf

AndrewMcN

15th Oct 2010, 11:01

Thanks this is good information.:ok:

Alber Ratman

15th Oct 2010, 14:59

Airbus AMM for A320's dictates tyre pressures depending on cover manufacturer and specification of cover..

It wasn't because the technician didn't know the pressure required, he didn't know how to use the equipment and didn't ask anybody that did. I never charge a cover with an outlet pressure from the regulator above 50 PSI of what I require. As said before, you will know the difference between a HP and LP setting when you purge the line. If you don't know who to use a trolley etc, ask someone who does. If the kit is unserviceable, stand up and don't use it.
Your safety is more important that 200 holiday makers being a couple of hours late, regardless of the pressures being applied..:)

Mike_s

16th Oct 2010, 20:16

ericferret

17th Oct 2010, 09:43

I reported to my line manager that in my opinion the pressure regulator on the nitrogen rig was dangerous as it was a high pressure regulator attached to low pressure tyre inflation equipment. I was given two or three coats of ignoring.

Within two months I was called to an aircraft where two contractors were having problems with the equipment and it was "jammed".

A Newbow tyre inflater was fitted and the operating handle could not be moved.

A quick look identified the problem and scared the sh*te out of me.

They wanted to put 125 psi into the wheel but had the regulator set to 125 bars (1875psi approx).

Rather gingerly I switched off the bottles and depressurised the line.

The only thing that saved them (and me) was the Newbow inflator I dread to think what the consequences of using something cheaper and nastier would have been.

Then we got a low pressure regulator!!!!!

Interestingly I note this this occurred at about the same date give or take a few months as the acccident at Manchester

Alber Ratman

17th Oct 2010, 12:42

Human factors such as the bean counters.. The use of the word pressures never crossed my mind as a pun!:O

10DowningSt

17th Oct 2010, 15:24

Alber,

he didn't know how to use the equipment and didn't ask anybody that did.

Human factors such as the bean counters.

I think you got it right first time. There were contributory factors, but that's what they were. I'm not sure sure that, for once, you can blame the beancounters.

AndrewMcN

17th Oct 2010, 17:03

We use the Newbow Tyre inflators on the output of the "Fast Tyre Fill Unit", they are great. This machine stores Liquid Nitrogen at 350 psi and we vaporize it to room temperature gas and supply it down 50ft hoses to fill tyres from empty in the Tyre Storage facility at different airlines in the UK. Each machine holds the equivalent of 20 cylinders of gas which cannot over pressurize the tyres as we cannot possibly exceed the min burst pressure of an aircraft tyre which is 4 x working pressure or about 800 psi for a 737 main gear. There is no cylinder handling and a handy gauge tells you when it is nearly empty. It is truly a safer option for tyres.

If you are interested visit | McNaughton Dynamics UK | Nitrogen, Oxygen and Cryogenic Pressurisation Servicing Units | (http://www.mcnaughton.co.uk)