Tyre pressures are crucial
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sorry Bus but i would say no lesson.
what is written in the checklists ?
no tyre pressure gage there ...?
you never check tyres press when it is written in the checklists ?
what is written in the checklists ?
no tyre pressure gage there ...?
you never check tyres press when it is written in the checklists ?
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What a cluster F@&k of an accident, immagine pulling reverse thrust the engines spool up but the reversers never deploy. Nightmare. Surprised that a 36% loss in pressure would cause a failure as I have seen tires that have lost 75% of their pressure make it to the gate w/o incident.
But then again my experience is mostly with widebodys. I would suspect a bad pressure guage, if all tires are this low, or ignorant reporting of the accident. If they were all low and the aircraft was heavy who knows.
Tires do not magically lose pressure at a controlled rate. Every tire is different. Another reason why tire pressure monitoring equipment is a nice feature.
Tires blow on big jets all the time and in my limited experience with corperate in the usa I can say with confidence for sure that there is less oversight. Most big jet operators have a program, often TP checks get doccumented every 24 hrs.
But then again my experience is mostly with widebodys. I would suspect a bad pressure guage, if all tires are this low, or ignorant reporting of the accident. If they were all low and the aircraft was heavy who knows.
Tires do not magically lose pressure at a controlled rate. Every tire is different. Another reason why tire pressure monitoring equipment is a nice feature.
Tires blow on big jets all the time and in my limited experience with corperate in the usa I can say with confidence for sure that there is less oversight. Most big jet operators have a program, often TP checks get doccumented every 24 hrs.
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Yeah, that tire blew for the same reason that many others have.. Got cut by FOD. Really with the few concorde's that ever flew it was only a matter of time, a concorde could have crashed decades ago for the same reason. Bet your bottom those tp's were checked prior to each flight.
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The swiss cheese model strikes again. Design factors may be something we can do nothing about but if the aircraft had been operated with tyre pressures as designed none of this would have happened, simples. That's the lesson for us.
Tyres can and do fail as little as 30% underinflated and some designs are higher stressed than others. Experience on other types is no excuse for complacency, that's why we have manuals and specs.
How often do we check tyre pressures? How many of us know how frequently they should be checked? What would you do if you checked tyres and found they were over pressure? Tyres do lose up to 5% px in 24hrs, this is a fact and not cause for rejection. Does your AMP have the necessary checks in it?
Tyres can and do fail as little as 30% underinflated and some designs are higher stressed than others. Experience on other types is no excuse for complacency, that's why we have manuals and specs.
How often do we check tyre pressures? How many of us know how frequently they should be checked? What would you do if you checked tyres and found they were over pressure? Tyres do lose up to 5% px in 24hrs, this is a fact and not cause for rejection. Does your AMP have the necessary checks in it?
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...and everytime a tyre should be changed on Concorde , it was a brand new one and not a "retreated" one...
thats what i have been told by some Buddies who used to work on it.
thats what i have been told by some Buddies who used to work on it.
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.... operator not checking the tyre pressure, which led to all four main gear tyres rupturing at just above V1 speed.
Investigators found that the Learjet's tyres, which are supposed to be inflated to 15.1bar (219lb/in2), had progressively lost about 2% of their pressure a day over a period of about three weeks before the accident, a typical leak rate for high-pressure tyres. Federal Aviation Administration certification rules allow for the tyres to lose as much as 5% a day.
Investigators determined that the tyres on the accident aircraft were inflated to about 9.66bar, 36% below the optimum pressure and well below the point at which they must be changed because of heat damage.
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I don't know anything about the FAA regs or indeed the Bizjet world, but there is one tiny point that sort of hits you in the face here.
What, precisely, was the aircraft doing for the 3 weeks prior to the accident?
Was it flogging around the USA?......or was it sitting on a ramp somewhere?...either way, when did it last see the attention of an engineer during this period and to what depth of routine servicing was it exposed?
How long in the FAA world can an aircraft be operated ( ok in this case it's a Bizjet so the operation will be different I assume from a scheduled carrier ) before it becomes mandatory for an engineer to perform a service check of any depth on the aircraft eg a daily/ night stop.
To say however that the industry is not aware of tyre px maintenance problems would see therefore to be bolleaux given that certainly from my experience tyres are invariably checked per se
I would guess those figures in the report are extrapollated from the manufacturers examination of the carcass and thus are based on a 2% loss from what would appear to be the last time the px were checked and recorded....which brings us back to my queries above.
What, precisely, was the aircraft doing for the 3 weeks prior to the accident?
Was it flogging around the USA?......or was it sitting on a ramp somewhere?...either way, when did it last see the attention of an engineer during this period and to what depth of routine servicing was it exposed?
How long in the FAA world can an aircraft be operated ( ok in this case it's a Bizjet so the operation will be different I assume from a scheduled carrier ) before it becomes mandatory for an engineer to perform a service check of any depth on the aircraft eg a daily/ night stop.
To say however that the industry is not aware of tyre px maintenance problems would see therefore to be bolleaux given that certainly from my experience tyres are invariably checked per se
I would guess those figures in the report are extrapollated from the manufacturers examination of the carcass and thus are based on a 2% loss from what would appear to be the last time the px were checked and recorded....which brings us back to my queries above.
Same old (very sad) story. Cut corners at your peril.
"If you think maintenance is expensive, try having an accident"
Don't know who first said that but it should be repeated louder and louder everyday.
"If you think maintenance is expensive, try having an accident"
Don't know who first said that but it should be repeated louder and louder everyday.
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Echo Turin's comments. Especially to the occasional Tits in the hangar offices, the retired Tit at Farnborough, the costly Tits at LGW and the passive Tits in Cologne..
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Association of Licensed Aircraft Engineers (ALAE) - Welcome
See you at the AGM
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Association of Licensed Aircraft Engineers (ALAE) - Welcome
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Without a complete serviceable set of wheels and tyres your clean aircraft becomes a clean statue, wheels and tyres are very overlooked and i fear to the deterement of many airlines.tyre pressures are ultra crucial and should be checked at every stop,if practicable as hot or warm tyres should not be checked for their pressures as this will be elevated by the heat held in the tyre casing and the heat in the brake cassette that slowly radiates away,it is recomended that the tyre should be tested with the back of the hand and if it is hot to the touch it is to hot to check and this would be deemed cool enough to be checked after three hours,there is a safety aspect as well an aircraft wheel inflated to 200psi is a bomb waiting to go off and many ground engineers have been seriously injured and some have been killed by hot tyres suddenly exploding for no reason,research has been carried out by the US navy on the destructive force in an exploding aircraft tyre and it has the equivalent force as the detonation of two and a half sticks of dynamite. deflated tyres can run for long enough for the a/c to clear most if not all runways but will have to be removed as well as its axle twin once the a/c is on stand,and both wheels have to be marked for overhaul and the flat one must also have further more investigative action carried out to determine the reason for deflation and the integrity if the wheel hub also has to be checked,I can safely say that the last 8 out of 10 deflation cases I have dealt with the axle twin once checked the wheel hub had failed NDT with stress cracks due to this being the remaining inflated wheel taking all of the weight.A tyre can also burst due to the rapid build up of heat from a long taxi with a heavily loaded a/c.Not only should tyre pressure be checked but shine the torch into the wheel and check the tie bolts they do shear and this can also lead to a slow loss of pressure in a wheel and it is also a reason to remove a wheel.Above all be safe around hot wheels and tyres if they have to be removed and are not going back on DEFLATE THEM it may be a noisy pain in the arse,it may save a life or two and stop and blast damage to the a/c and anything within an easy 50-100 yard radius.
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Learjet requires the tyre pressures to be checked prior to the first flight of each day..This should be either done by maintenance staff or crew should have an authority to do so. Biz jets can often be away from the regular organisation that maintains them, this is where it becomes a problem...Unlike airlines they do not fly regular routes....
I have recently moved into the corporate world from the airlines and it is very different...Some good , some not so...
I have recently moved into the corporate world from the airlines and it is very different...Some good , some not so...
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Wheely King I agree with most of what you say, but not this bit:
Yes it is possible that loss of tire px can be caused by a cracked hub but I have never in 15 years seen any cases where the axle mate hub has been cracked by running with an underinflated partner. The tire carcass itself may well be overstressed in such cases and the tire companies will automatically scrap any tire marked "deflated" or "partner", however the wheel hub should still be OK.
Your comments about tiebolts are also worth note, as a single tiebolt failure can be tolerated for a short time with no apparent symptoms. In time however the bolt either side of the failed one will itself fail in overstress and then the deformation from landing stresses will allow the center packing to extrude out between the half hubs resulting in instant deflation. This is a real issue that can affect aircraft like 737s with outboard hub fairings.
I can safely say that the last 8 out of 10 deflation cases I have dealt with the axle twin once checked the wheel hub had failed NDT with stress cracks due to this being the remaining inflated wheel taking all of the weight.
Your comments about tiebolts are also worth note, as a single tiebolt failure can be tolerated for a short time with no apparent symptoms. In time however the bolt either side of the failed one will itself fail in overstress and then the deformation from landing stresses will allow the center packing to extrude out between the half hubs resulting in instant deflation. This is a real issue that can affect aircraft like 737s with outboard hub fairings.
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We have just had a B737 on an emergency air turnback due to a thrown tread , the tyre pressure was checked and topped up the night previous but was known to be leaking ...........No time / inclination to change a wheel so just top it up again , It'll be OK , Oh yeah !!!!!!!!!!!!!!!!!
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I have miss written slightly concerning the deflation of an axle twin , the 8 out of 10 I have seen has been the result of a burst (747-200F) and we have found that in the twin that remained at operating px the o/b hub has cracks to the spokes but this was probably from turning of the a/c (so I have since been informed).
The loss of one tie-bolt(wheel on a/c ) this wheel must be removed (32-45-03) then I agree the bolts either side of the missing one have to be replaced,although there has been a s/b about time life programme where all the bolts are replaced for a new set and are then replaced after 4000 cycles and carry out dvi for every 4 tyre changes and mpi at 5 or o/h
The loss of one tie-bolt(wheel on a/c ) this wheel must be removed (32-45-03) then I agree the bolts either side of the missing one have to be replaced,although there has been a s/b about time life programme where all the bolts are replaced for a new set and are then replaced after 4000 cycles and carry out dvi for every 4 tyre changes and mpi at 5 or o/h
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underinflated tires fail taking a DC-8 out of the air (1991).
http://aviation-safety.net/database/record.php?id=19910711-0
July 11, 1991 Jeddah Saudi Arabia a DC-8 was lost killing everybody on the jet. For me this accident crystallized the importance of proper tire inflation. If you haven’t read the accident analysis it is worth your time as it makes absolutely clear the terrible hazards of improper tire servicing/conditions.
July 11, 1991 Jeddah Saudi Arabia a DC-8 was lost killing everybody on the jet. For me this accident crystallized the importance of proper tire inflation. If you haven’t read the accident analysis it is worth your time as it makes absolutely clear the terrible hazards of improper tire servicing/conditions.
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Some thoughts:
Very few biz pilots own calibrated tire pressure guages sufficient to check jet tires...fewer still check everyday prior to flight...fewer still would have checked prior to a flight at midnight, as such was the Lear 60 departure time. Few pilots would have actualy given more then a cursory look at thier tires in the dark, with a flashlight, much less gotten on their hands and knees to check tire pressures.....
Fewer still are pilots that actualy know what the rated tire pressure is for thier aircraft..fewer still are the pilots that check, know the number, and will scrub a flight at midnight because no nitrogen is available at that time to pump them up...
If I sound like a broken record, my apologies...just another rant about professional responsibility....
Very few biz pilots own calibrated tire pressure guages sufficient to check jet tires...fewer still check everyday prior to flight...fewer still would have checked prior to a flight at midnight, as such was the Lear 60 departure time. Few pilots would have actualy given more then a cursory look at thier tires in the dark, with a flashlight, much less gotten on their hands and knees to check tire pressures.....
Fewer still are pilots that actualy know what the rated tire pressure is for thier aircraft..fewer still are the pilots that check, know the number, and will scrub a flight at midnight because no nitrogen is available at that time to pump them up...
If I sound like a broken record, my apologies...just another rant about professional responsibility....
The loss of one tie-bolt(wheel on a/c ) this wheel must be removed (32-45-03)
A320 for one and I believe B767 with some operators allow one tie bolt missing for a limited period.
Still got to get the wheel off and check that the other end hasn't trashed the brake unit or inside of the wheel but hey-ho.
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Wheelyking someone's been reading his CMM LOL 
The time life program you refer to is an alternative to doing MPI on the bolts, on the logic that what you lose in hardware scrappage costs you save on reduced labor costs. That works fine as long as you know the fitment date of the original bolts!
A little story for you. An airline I used to know some years back operated 747-100 and 737-4/500. Their workshop practice was to clean and NDT tiebolts then throw them all in a tray together and pick out the required number when they built a wheel. What they failed to realise is those 2 aircraft types, of some 20 years age difference, used the same P/N tiebolt and they couldn't understand why on their new 737s they had a rash of age related tiebolt failures! At least one was a multiple bolt failure causing tire deflation because the first broken bolt was hidden by the wheel fairing. And as Turin says the migrating bolts mullered the brake.
So it's not only flight crew where complacency and sloppy practice can have serious consequences!
The time life program you refer to is an alternative to doing MPI on the bolts, on the logic that what you lose in hardware scrappage costs you save on reduced labor costs. That works fine as long as you know the fitment date of the original bolts!
A little story for you. An airline I used to know some years back operated 747-100 and 737-4/500. Their workshop practice was to clean and NDT tiebolts then throw them all in a tray together and pick out the required number when they built a wheel. What they failed to realise is those 2 aircraft types, of some 20 years age difference, used the same P/N tiebolt and they couldn't understand why on their new 737s they had a rash of age related tiebolt failures! At least one was a multiple bolt failure causing tire deflation because the first broken bolt was hidden by the wheel fairing. And as Turin says the migrating bolts mullered the brake.
So it's not only flight crew where complacency and sloppy practice can have serious consequences!