BELL 412 Transmission Oil Leak , Offshore
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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.
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.
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Hmmmm...
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
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
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.
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Run dry requirements
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
[(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
Last edited by jetA1pilot; 8th Aug 2010 at 11:26.
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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
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
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412 Xmsn
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
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
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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
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
Last edited by maeroda; 9th Aug 2010 at 12:18.
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Loss of lube requirement test
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.
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.
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
As others have said, follow the RFM or Company procedure. Don't second guess or assume
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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.
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.
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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.
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Never assume is good advice: 7th Anniversary of Newfoundland S-92A Accident
But this also shows that not every RFM is that helpful.
But this also shows that not every RFM is that helpful.
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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...
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...
