goinv
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Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 1:13 am

I was always under the impression that a mechanic who worked on (lets say) the starboard engine was not allowed to carry out similar work at the same time on the port engine.
This was to reduce the risk associated with a possible mistake being made on both engines with obvious disastrous results.

Today I have been talking with an ex RAF engineer who says this is wrong and the rigourous checks would highight potential errors.

Was my understanding an urban myth or are mechanics not allowed to do the things I have highlighted ?
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Tristarsteve
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 1:56 am

In our airline we have a twin engine policy that basically says one mechanic per engine. This came from Etops rules which also have this. But this does not stop one mechanic from servicing the oils on both engines.
In the old days there was always an inspector to check your work, but nowadays licensed mechanics work on their own and certify their own work, so except for controls which need duplicate inspections ( or RII in the USA) most work is not checked. Hence the twin engine policy.
 
AirframeAS
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 2:18 am

Quoting Goinv (Thread starter):
mechanics not allowed to do the things I have highlighted ?

They teach us that ALOT in A&P Technician school. My A&P school's dean is the chief inspector at US Airways.
A Safe Flight Begins With Quality Maintenance On The Ground.
 
Matt72033
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 2:50 am

In our Hangar, every engine workcard states on the top that different technicians shouldbe used on each engine! it makes sense really....helps cut out mistakes!

Like Steve mentioned, this doesnt include oils
 
XXXX10
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 7:45 am

http://www.aaib.gov.uk/cms_resources/dft_avsafety_pdf_502864.pdf

Thia link shows an investigation on a 737 incident were both engines had low oil pressure after a boroscope inspection, from what I can deduce they were carried out by the same engineer.
 
fr8mech
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 10:10 am

Our ETOPS rules state, simultaneous tasks. The mechanic can't change the main oil filter on both engines, but he can change the oil filter on one and the fuel filter on another.
When seconds count...the police are minutes away.
 
2enginesonly
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 10:20 am

Over here in the Netherlands we have, besides the ETOPS requirements, also the 'critical tasks'.
This basically is the same as for the engines except that it's also valid on other systems.
For instance, one person is not allowed to replace both wheels on the same axle....that has to be performed by 2 persons. Seperate axles is no problem, just as long as they're not on the same axle.
This is for all a/c....not limited to ETOPS a/c only.
I've got a list somewhere of the systems concerned but it's covers several systems.

Arjan
 
EMBQA
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 10:34 am

Quoting Goinv (Thread starter):
I was always under the impression that a mechanic who worked on (lets say) the starboard engine was not allowed to carry out similar work at the same time on the port engine.

It must be a UK thing because I've never seen that in any US airlines GPM.
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Buzz
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 8:22 pm

Hi Goinv, Buzz here. Over here in the Colonies (grin) we call that "Dual Maintenance" and where I work it's allowed... except on ETOPS aircraft. As a more practical matter on our crew we try to avoid having the same guy do the same task on both engines.

I recall hearing a tale about an Eastern Airlines L-1011 that left Miami in the 1980's after an overnight check where the oil screens were all changed by the same guy. Problem was that this time the "new" oil screens didn't come from the shop with O-rings. So the guy (working tired in the middle of the night I imagine) plugs in the new oil screens, and considered it good.

After takeoff, the Flight Engineer noticed that one of the engines was losing a lot of oil. So shut down the engine, and turn back to Miami.

After they have the engine secured and aircraft turned around the F/E saw that both of the other engines are really, really low on oil. So they re-start the shut down engine, and shut down the other 2 engines... landing successfully at Miami with people in life vests in case of a water landing.

I forget the logic that deploys the RAT on an L-1011, it was deployed on landing. Somebody had never seen it before and asked "what's that for?". Somebody replied that's the "trolling motor" for after you ditch. (you can slowly go fishing) (grin)

g'nite
 
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HAWK21M
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 8:36 pm

Its all Depended on the Companys SOP.
Out here.On Twin Engines If work is performed Simultaneously.Then its done by Different persons to reduce the Chances of error Impact.
regds
MEL
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Tristarsteve
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RE: Aircraft (engine) Maintenance Protocols

Fri Jun 02, 2006 10:02 pm

Quoting Buzz (Reply 8):
Eastern Airlines L-1011 that left Miami in the 1980's after an overnight check where the oil screens were all changed by the same guy.

They were Tedeco plugs (chip detectors.) After that incident Rolls changed the design so you could not fit them without o-rings.
The problem was that when you drew the box of plugs from stores they always came (and still do) with o rings fitted, this box didn't because it came a different route and th rings were never fitted before issue.
Now on a RB211 if you try to fit a chip detector without an oring a pin drops into the oring groove and stops you fitting it.
 
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HAWK21M
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RE: Aircraft (engine) Maintenance Protocols

Sat Jun 03, 2006 2:24 am

Quoting TristarSteve (Reply 10):
They were Tedeco plugs (chip detectors.) After that incident Rolls changed the design so you could not fit them without o-rings.

Why wasn't it detected during Ground run.

Quoting TristarSteve (Reply 10):
Now on a RB211 if you try to fit a chip detector without an oring a pin drops into the oring groove and stops you fitting it.

Is this applicable to RB211-535s
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Buzz
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RE: Aircraft (engine) Maintenance Protocols

Sat Jun 03, 2006 9:46 pm

Hi TriStar Steve, Buzz here. Thanks for letting me know the rest of the story about the chip screeens on an L-1011. I figured they'd be similar to what the CFM56 has.

And Hawk21M... I don't know why they didn't find the leak at idle after oil system work.

g'day
 
fr8mech
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RE: Aircraft (engine) Maintenance Protocols

Sun Jun 04, 2006 3:09 am

Quoting Buzz (Reply 12):
And Hawk21M... I don't know why they didn't find the leak at idle after oil system work

Because not all maintenance programs require an engine run after pulling a QD magnetic chip detector. Don't know about the L-1011, but as I recall, the PW2037 does not require a run after checking the detector. I'd need to double check that.
When seconds count...the police are minutes away.

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