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rupigill
1st Aug 2010, 03:13
ATTENTION BELL 412 OFFSHORE PILOTS

1.On 27 July 2010 I was flying a Bell 412 for offshore crew change in support of a floater about 100 miles away with 7 passengers on board.The co-pilot was on controls at cruise 2000 ft AMSL . Around 54 miles outbound the Transmission oil pressure light came ON, crosschecked with the oil pressure guage and found oil pressure at 30 psi and dropping. I immediately took over the controls and reduced power to approx 45%,commenced descent to 500 ft and turned towards the nearest landing site available, the coast line fortunately 17 miles away.Completed actions as per the RFM and warned the passengers of the emergency and likelyhood of landing on water.

2. Continued ,constantly monitoring the transmission temeprature which remained steady at 60 celsius and looking for any signs of further deterioration in terms of vibrations and increase in temeprature.Continued passing the the GPS position frequently to nearest control tower and other company aircrafts to make SAR easier. The pressure continued dropping and last noted was around 0 psi. Landed safely at the coastline away from the high tide line and switched off.

3. On inspection found last about 500 ml oil flowing from the hell hole.The inspection windows were empty and tail boom splashed all over.The GPS position was passed and within 5 minutes a dornier aircraft of indian navy who was monitoring the calls flew overhead and reported all safe to the control tower.Mobiles came in handy and within 5 minutes all concerned were contacted. The police and local help came soon thanks to 108 service of Andhra Pradesh (akin to 911 of USA).

4. Later it was found that a flexible hose in the system had given way.The hose was 24 yrs old ,8 yrs on shelf and 16 yrs on the aircraft.

5.Good CRM and cool Captain, Copilot and passengers saved the day and lives of all. Above all not to forget the GOD Almighty who blessed us with those crucial 16 minutes.

5.Weather was as in monsoons in India,Sea state could have been anything between 4-6 and landing on water would have had its connected problems. A word of CAUTION you may not always get 16 minutes ,will depend upon how fast the system gets drained out.

Shell Management
1st Aug 2010, 09:15
rupigill

Many thanks for taking the time to saher your experience. Perhaps you could post this in the Rotorheads section where this would get far more exposure to helicopter crews.

The crew of the Cougar S-92A on 12 March 2009 had less than 10 minutes before there gearbox failed after an oil loss.

rupigill
1st Aug 2010, 11:14
Shell Management,

Thanks a lot ,put it under rotorheads. Just thought wide publicity may come in handy to someone , someday and save precious lives.

Rupi Gill

spinwing
1st Aug 2010, 12:44
Mmmm ...

Well done .... were you flying out of Rajahmundry or Vijayawada?


:D

maeroda
1st Aug 2010, 12:52
Hello.

Well done boys!!:ok:

Some years ago my coworkers were flying a 1200TT AB412EP on water when suddenly XTMS light press went ON with XMSN press zeroed in seconds.
The captain and copilot were alone on board; they headed onshore and landed after 17' oil pressure was lost.
The flight was released after a 600hrs overhaul, the helo being flight tested for TEN hours before releasing the ship back to her Hems base.
Oil was lost in flight after 4 flight hours from start up, tail was totaly oil soaked, temperatures never went up over red line; it was wintertime.
By the way this XMSN is actually certified for sure with 30' run dry capability and operator went on with it for other 300 hours being cleared by Agusta for that.
Despite that we were forced to stop after a while after daily sump chip detection and Agusta decided to withdraw the trasmission.

Some time after the incident we discovered the cause of the sudden leak: the main trasmission oil chip detector in the low sump (known as "the big CHIP") has been istalled upside down after inspection by the flight engineer, letting the oil to go out after 10 hours of duty.

Normally I use to go for 24/7 140Nm trips in deepwater with EP's and ditching is a big concern even in the center of the warm, low waved, SAR well covered mediterranean sea.
Actually I rely deeply on the rugged old style Bell alluminium B412 trasmission AND on PNR & windtemps route calculations.
A bit of luck never hurts, also.

Cheers
Maeroda
Italy

rupigill
1st Aug 2010, 13:36
Flying out of Vizag(Vishakhapatnam). Thanks a lot for viewing,a wide publicity may help somebody someday in future.

rupigill
1st Aug 2010, 13:42
Here since tranmission never ran dry, the defective part was replaced & the aircraft was flown next day by me again . A day later after the necessary checks it was off again for revenue sorties.My eyes scan the gauges more often now.

thanks & happy landings

JHR
1st Aug 2010, 15:54
I always understood that the transmission oil temperature sensor required oil flow work properly. if there is no oil pressure and no flow the temperature will not increase. If you lose oil pressure don't rely on the temperature gauge to let you know how hot transmission is.

JHR

Soave_Pilot
1st Aug 2010, 18:19
I always understood that the transmission oil temperature sensor required oil flow work properly. if there is no oil pressure and no flow the temperature will not increase. If you lose oil pressure don't rely on the temperature gauge to let you know how hot transmission is.Is that for every aircraft mate? Or just the 412?

Droopy
1st Aug 2010, 18:52
Top result, well done, especially for the quick posting on Prune, but....I immediately took over the controls and reduced power

weren't you loading yourself up somewhat in CRM terms? the other pilot is described as Capt therefore capable so as commander you took on the handling and decision making role?

JHR
2nd Aug 2010, 00:04
I can not speak for all types of helicopters. All the Bell helicopters I have flown would not register reliable oil temperature with out oil pressure.

JHR

rupigill
2nd Aug 2010, 00:32
The other pilot though adequately experienced was not cleared to fly as captain ,hence the need to take over the controls and fly myself. Thanks.

Nigel Osborn
2nd Aug 2010, 03:59
I spent a year flying a 212 out of Vizag, Rajah, Yanam & Juhu; very interesting during the monsoon season!

You did the right thing because, to be honest, that was the obvious option. Unfortunately too many pilots don't take the best option.:ok:

spinwing
2nd Aug 2010, 04:38
Mmmmm .....

Vizag/Rajah ops quite good .... you need to work out of Chennai for awhile for REAL frustration to get you!


:ugh:

Nigel Osborn
2nd Aug 2010, 07:44
Mmmmmmmmmmmmmmmmm

I forgot to mention I also flew a 212 out of Chennai!:ok:

spinwing
2nd Aug 2010, 08:20
Mmm ...

Ha .... then you know exactly what I mean .... :eek:

Take care Nigel


;)

500e
2nd Aug 2010, 10:55
JHR
Tend to agree gear box temp is normally taken from the oil flow not casing temp, have seen a few gear boxes (not rotary) wired with thermocouples to check individual bearing\ shaft temps, usually for development purposes, the problem with this is there can be large variations in temp due to heat sink and air flow.

jetA1pilot
7th Aug 2010, 08:31
I think ur correct JHR - oil temperature gauge is meaningless as to actual temperature & thermodynamic situation inside the transmission. Don't rely on the gauge in this situation.

The temperature probe is measuring oil temp i.e wet line, on the pressure side of the system, up towards jets 6 or 7 - the higher portion of the txmsn casing. No oil pressure = no oil carrying heat away from all the nasty moving metal bits = no meaningful reading from the oil temp probe, thats just residual heat u r seeing on the gauge which will cool down in time.

Also, perhaps more important is that the input bearing on the main driveshaft is not getting any lubrication! Jets 5&6 if I recall - again, no oil pressure = no lubrication and no heat dissippation, and that bearing is running around 6000 rpm with no lube!

Have lost the txmsn oil (pressure & the oil itself) in a 412EP at 4500' in cruise. Was due to same problem as maeroda mentioned in his incident below; had happened once before at same company. Worth checking that debris monitor & knowing which way the part plate should be! Ran ours dry for 12 mins during decent and emerg landing - thank goodness for Bell's rugged engineering. Longest 12 mins of my life.

FYI - I was also under the impression that there was a "30 minute run dry certification". Response from Texas in my subsequent investigations was "sorry, no such FAA requirement for civilian machines......" Good food for thought - again, don't be misled on the time you have available to run without oil - think ditch/land as soon as possible but as mentioned already, sea state & SAR situation will influence risk of ditching versus pushing the transmission to a hard surface landing.

We were all lucky and can thank the design team that over-engineered the transmission so well. Another captain I flew with lost the oil in a 212 many years ago - from a 1000' he'd hardly got down to the water before the txmsn failed catastrophically & they went in, he was the only survivor.

Get it down low & slow IMHO and don't be afraid of ditching.....

outhouse
7th Aug 2010, 10:05
Jet,
My view follows yours, the temp sensor and over temp switch are showing oil temp, and as long as they are in oil then the delivery of information is accurate (to calibration limits). Once they are out of the oil stream then NO. I have experienced a decrease of temperature indications after oil loss, bulb now measuring air temperature at sensor. You can smell increase of case and internal bits temp and stress as it increases when you see the indicator increase it's to late. Secondary indications vibration, and stress noise, decrease in NR (hunting and unstable) increase in TQ (unstable and hunting with engine power indications) and engine trying to maintain power you should be not be flying and awaiting collection by friends.
:ok:

500e
7th Aug 2010, 12:30
jtA1
"FYI - I was also under the impression that there was a "30 minute run dry certification". Response from Texas in my subsequent investigations was "sorry, no such FAA requirement for civilian machines......" Good food for thought - again, don't be misled on the time you have available to run without oil - think ditch/land as soon as possible but as mentioned already, sea state & SAR situation will influence risk of ditching versus pushing the transmission to a hard surface landing.

We were all lucky and can thank the design team that over-engineered the transmission so well. Another captain I flew with lost the oil in a 212 many years ago - from a 1000' he'd hardly got down to the water before the txmsn failed catastrophically & they went in, he was the only survivor."
maroda
"By the way this XMSN is actually certified for sure with 30' run dry capability and operator went on with it for other 300 hours being cleared by Agusta for that.
Despite that we were forced to stop after a while after daily sump chip detection and Agusta decided to withdraw the transmission."
Again 2 professionals who have a totally different understanding of the gear box they fly, I presume they are talking about the same type Helicopter

outhouse
7th Aug 2010, 14:55
PLEASE ALL.
Regardless of certification needs even the 139 RFM makes no mention of any 30 min run dry time. Look on it as a slightly less pucker factor as you head down.
The bell 212 412 has no run dry ability at all. No oil, get the sucker on the deck ASAP.
An old fart.
:ok:

WhirlwindIII
7th Aug 2010, 16:55
rupigil

With upfront apologies for my lack of understanding this post, please; and congratulations on making it to the beach.

You mention ".....crosschecked with the oil pressure gauge and found oil pressure at 30 psi and dropping (my emphasis)."

OK. Understand.

Question please.

Was flying to the beach what was supposed to have happened IAW the RFM?

VR

WIII

Oldlae
7th Aug 2010, 20:33
In my day, flexible hoses with a rubber or synthetic lining would have been retired in the UK at 10 years, if the hose was a teflon lined hose it would have been "on condition" the part number should indicate the lining used, IIRC.

Encyclo
7th Aug 2010, 21:37
Even a 6 month old flex line will not be trouble free if it is chafing on something :ugh:

That is why the aircraft needs to be inspected per the ICAs :ok:

jetA1pilot
8th Aug 2010, 11:00
500e - by today's standards, yes - if you wanted to design & certify a cat A helicopter for offshore transport, FAR part 29 certification stipulates:

[(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flightcrew of the lubrication system failure or loss of lubricant.]

This of course led to the big stink with the S92 which claimed excemption since they deemed loss of lubricant to be "extremely remote" - they certainly made use of the leeway/loophole.....nuff said on that, it's running in another thread.

Back to this topic - info I garnered following our loss of txmsn oil was that back at time of certification of the Bell 412, (remember it first flew late 70's) this wasn't a requirement. That's hearsay and a very grey area; If someone has first hand info from the 1970-1990 era Rotor Drive System certification requirements & subsequent amendments (for EP revisions), please let us know.

J

maeroda
8th Aug 2010, 15:55
Hello.

As far as I know no mention about 30' Run Dry will ever be printed on a RFM, even being that a FAR 29 XMSN basis certification rule for all trasmissions having lubrication oil external tubing.

Actually I've been flying the 412 models since 2000 and never read anything anywere about 30' run dry certification on this type, neither in the 212 or 205.

Said that, I know Agusta's Experimental branch once got the trasmission run dry tested in mid '80; they started up a 212 XMSN shafted into a test facility and after a while they suddenly drained the oil out from the sump keeping her going on for 30', then they shut down the whole thing.
Thorough post damage inspection was carried out and results where presented to the Italian DoD who by the way was the issuing authority for this experiment.
The chief engineer at the company I work for was one of those guys in the run dry test.
Now, all pilots flying know that landing ASAP is mandatory by RFM after a XMSN LOW PRESS in most helicopters; on the other side old 412 pilots and engineers know about the capability of this helicopter to carry out a 30' run dry at VY in such an emergency.
This capability was never certified black on white, though.

In another perspective we should consider how many Huey crews got the arse back home with their ships battered to scrap in Vietnam.
The 412 transmission comes from that age; is basicaly the same as before apart of more alluminium and less magnesium, some strength added to deliver more power to the rotor, and has been war tested unlike most helicopters flying today.

In my personal opinion and having gathered experience from co-workers that kept running for 17' without any oil and subseguently having flown the same ship for another 300hours under manufacturer permission and control, I would say I would absolutely prepare myself and everybody on board for a diching if such emergency would occur, going down to low altitude lowering pitch to VY or less; at the same time I would use every minute this sturdy transmission would give me in order to get as near as possible to some shore, ship or SAR area.

Cheers

Maeroda

WhirlwindIII
8th Aug 2010, 18:36
maeroda

Interesting. I remember a UH1 crew putting their helicopter down in RVN due to XMSN pressure failure. They didn't crash in to the jungle growth but the first open area did just fine.

I think pushing the limits on such things is an invitation to unfortunate results, but ditching in a rough sea could provide the same.

Guess we could say this gray area is a PIC choice of exercising the least of evils over time available, given all circumstances.

Thanks.

WIII

maeroda
9th Aug 2010, 11:37
Jet A1 Pilot,

I remember early 412's where FAR 29 certified for cat B operations;
FAR 29.927 (latter copied & pasted into JAR-29 and Easa CS-29) requirements for cat B ops where at least to assure 15' run dry in autorotation and flare/touch down.
Meanwhile RFM dictated 3 drills in "emergency procedures" pages:
1) land immediatly,
2) land ASAP,
3) land as soon as practical,
being "land immediatly" compulsory for XMSN OIL PRESS, XMSN OIL TEMP, BAGAGGE FIRE for example.

When cat A operations popped out the ship has been certified to fullfill those requirements; they changed some RFM pages, adding cat A procedures for t/o & landing, also performance was in due to change in better way.
In the RFM intro pages Bell and Agusta stated the helicopter was now certified under FAR 29 for Cat A & B operations and, magically, the emergency drills become 2:
1) land ASAP
2) land as soon as practical
being now all items related to XMSN OIL addressed to the first option (not an option actually). "Land Immediatly" was writted off the manuals.

So what?
Despite the age of the helicopter Bell and Agusta (in the last years) had changed the requirements of the trasmission for EP models to fullfit part 29.927; we know this part requires 30' run dry capability for all trasmissions installed on cat A helicopters, unless oil lubrication system failure could be considered extremely remote (see Sikorsky downturn).
So, as I understand it, the B412 trasmission can be considered to have 30' run dry capability if FAR/JAR-29 type certification has been released and compliance to FAR 29 is writted on the RFM.

What about pushing the limit?
IMHO nobody with good sense is allowed to do so in flight operations; simply the pilot has some minutes left at minimum power to decide were and how he is going to dich before all the damn thing tears apart.
Obviously IF the XMSN is well mantained and inspected.

cheers
maeroda

ebr649
9th Mar 2016, 17:08
The requirement for Part 29 helicopters is that the main gear boxes should be subjected and pass 30 minute loss of lube test. Part 27 helicopters are subjected to 15 minute loss of lube test.
That do not mean these helicopters can perform for 30 minutes. As soon as you see the low pressure light you need to follow the RFM emer. procedures.

maeroda
11th Mar 2016, 16:30
I think nobody said something different from your statement, here.

Apate
12th Mar 2016, 12:21
Be careful though, not all Part 29 aircraft have 30 minutes 'loss of lube' capability. The requirement was established under an Amendment to the rules at some point and there is no requirement for retrospective compliance. Many, many aircraft do not comply!

As others have said, follow the RFM or Company procedure. Don't second guess or assume :=

riff_raff
13th Mar 2016, 03:28
Just came across this older thread. Read thru the posts and there was one (#7) from the OP'er that was very interesting. He stated after the MRGB experienced near total loss of oil due to a failed flex hose and was flown for a period with very low oil pressure, the failed hose was replaced and the aircraft was placed back into service. If true, this seems quite odd. The gears/bearings in the MRGB are oil cooled. They each receive a carefully metered flow of oil for cooling from oil jets. The oil jet flow will be greatly reduced if the oil pressure drops significantly, and this can result in the gears and bearings not being cooled sufficiently. If the gears and bearings are overheated it can result in a loss of temper and reduced mechanical properties. The only way to determine if the gears and bearings experienced any loss of temper would be to remove and inspect each one. The lube oil temp sensor does not provide a measurement of individual component temps. It only measures the fluid temp at its sensing face.

With newer rotorcraft transmission designs there has been an effort to reduce or eliminate the use of flex hoses for flight critical systems like lube oil circuits. Most of the main rotor gearbox oil pipes are now integrally cast into the housings, which minimizes the potential for leaks.

riff_raff
13th Mar 2016, 07:38
The subject of rotorcraft certified under FAR part 29 loss of lube testing is an extensive topic of debate. What some have pointed out is that the test procedure only requires one gearbox to pass the 30 minute standard. This does not mean every MRGB in service will do the same. The problem is that to get a statistically relevant result from MRGB loss of lube tests would require testing a large number of gearboxes to failure. As you can imagine this would be quite costly. Even then, due to the large number and range of variables involved with an MRGB loss of lube event, it would be difficult to guarantee every gearbox in service would meet the full 30 minute requirement.

zalt
13th Mar 2016, 21:03
Never assume is good advice: 7th Anniversary of Newfoundland S-92A Accident (http://aerossurance.com/helicopters/2009-canadian-s-92a-accident/)

But this also shows that not every RFM is that helpful.

Viper 7
15th Mar 2016, 12:40
It has been quite a while since I flew the 412, but are the sensors for the oil pressure low caution light and the guage not in differnet places in the gearbox to help diagnose a true loss of oil vs. a failed transmitter or other less serious faillure?

I seem to remember the temp warning light and guage were similar.

It's been a while and a new medium multi since then though, so be gentle...

:O