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Aircraft (engine) Maintenance Protocols  
User currently offlineGoinv From United Kingdom, joined Jan 2005, 264 posts, RR: 2
Posted (8 years 2 months 2 days 8 hours ago) and read 3573 times:

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 ?


Be who you are, The world was made to measure for your smile. So Smile.
13 replies: All unread, jump to last
 
User currently offlineTristarSteve From Sweden, joined Nov 2005, 3982 posts, RR: 34
Reply 1, posted (8 years 2 months 2 days 8 hours ago) and read 3562 times:

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.


User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 2, posted (8 years 2 months 2 days 7 hours ago) and read 3557 times:

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.
User currently offlineMatt72033 From United Kingdom, joined May 2005, 1617 posts, RR: 4
Reply 3, posted (8 years 2 months 2 days 7 hours ago) and read 3547 times:

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


User currently offlineXXXX10 From United Kingdom, joined Jan 2000, 777 posts, RR: 0
Reply 4, posted (8 years 2 months 2 days 2 hours ago) and read 3518 times:

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.


User currently offlineFr8mech From United States of America, joined Sep 2005, 5365 posts, RR: 14
Reply 5, posted (8 years 2 months 2 days ago) and read 3501 times:

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.
User currently offline2enginesonly From Netherlands, joined Jun 2005, 91 posts, RR: 0
Reply 6, posted (8 years 2 months 1 day 23 hours ago) and read 3500 times:

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


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 7, posted (8 years 2 months 1 day 23 hours ago) and read 3495 times:

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.



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineBuzz From United States of America, joined Nov 1999, 697 posts, RR: 21
Reply 8, posted (8 years 2 months 1 day 13 hours ago) and read 3463 times:

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


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 9, posted (8 years 2 months 1 day 13 hours ago) and read 3459 times:

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



Think of the brighter side!
User currently offlineTristarSteve From Sweden, joined Nov 2005, 3982 posts, RR: 34
Reply 10, posted (8 years 2 months 1 day 12 hours ago) and read 3447 times:

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.


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 11, posted (8 years 2 months 1 day 7 hours ago) and read 3418 times:

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



Think of the brighter side!
User currently offlineBuzz From United States of America, joined Nov 1999, 697 posts, RR: 21
Reply 12, posted (8 years 2 months 12 hours ago) and read 3389 times:

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


User currently offlineFr8Mech From United States of America, joined Sep 2005, 5365 posts, RR: 14
Reply 13, posted (8 years 2 months 7 hours ago) and read 3369 times:

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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