Exchanging Parts for troubleshooting

[Stepclimb]

Allow me to pose a hypothetical situation....
Aircraft 1 in service with a 121 carrier experiences a fault with its elevator artificial feel system. The fault is traced to a LRU "box" and MEL'd. To clear the MEL, the box is swapped with one from airplane 2 and all ops checks good on airplane 1.
Now airplane 2, with the faulty circuit from airplane 1 flies a few legs and then experiences an elevator artificial feel fault....and you guessed it, gets MEL'd.
This scenario is repeated as the faulty elevator feel circuitry makes its rounds amongst the fleet. Mechanics will tell you that they are "troubleshooting" to determine the cause of the fault.
How many out there have seen this and what regulations or standards are out there to prevent this sort of thing?

 

[bocefus]

Not uncommon, no regulation exists to prevent this.

 

[IndyGTP]

We try not to do it where I'm at. I think I've only seen it on one occasion. The 'defective' part removed for troubleshooting is the known problem so therefore it should be green tagged and sent for repair.

But hey whatever works. As long as the FAA doesn't catch it, they can buy the company more time to get the part cheaper.

Try not to get involved in this paper trail. If the feds ever did find it they would come after whoever issued the MEL and whoever deferred it in the logbook.

 

[sbn340mech]

Yeah thats a strange situation. I'm trying to figure out how the bad part from a/c 1 ended up on a/c 2.

where I used to work, "rotable" and "expendable repairable" parts required servicable tags, signed off by QA. No part got installed on an a/c without one. So the part from a/c 2 would have to of been removed, inspected, a servicable tag initiated, signed off, before it could be installed on a/c 1, op/c'd and the mel cleared. a/c 1 can go bye-bye. Now your stuck with a bad part, with the copy of the servicable tag (it's a 4 part tag) and in the "reason for removal" section you put why it was removed from the aircraft, and it all goes to the parts counter so it can be shipped out for repair.

Sorry for the long post, but I wanted to be clear. I wouldn't want my name anywhere near that work

 

[Stepclimb]

Yeah thats a strange situation. I'm trying to figure out how the bad part from a/c 1 ended up on a/c 2.

where I used to work, "rotable" and "expendable repairable" parts required servicable tags, signed off by QA. No part got installed on an a/c without one. So the part from a/c 2 would have to of been removed, inspected, a servicable tag initiated, signed off, before it could be installed on a/c 1, op/c'd and the mel cleared. a/c 1 can go bye-bye. Now your stuck with a bad part, with the copy of the servicable tag (it's a 4 part tag) and in the "reason for removal" section you put why it was removed from the aircraft, and it all goes to the parts counter so it can be shipped out for repair.

Sorry for the long post, but I wanted to be clear. I wouldn't want my name anywhere near that work

Thanks for the replies. Keep in mind; this hypothetical situation occurs at a hub airport with company maintenance but nowhere near QA and the main company facility. Aircraft 1 has about an hour sit in the hub before heading out.

It seems quite common for parts to be exchanged between aircraft for troubleshooting reasons (no tags being generated). In this situation, after the part from aircraft 2 is installed in aircraft 1, all is well after a ground ops check. The logbook entry in aircraft 1 reads "R/R elev artificial feel circuit with part #xxx, serial #xxx IAW maint manual blah blah: ops check good-MEL cleared signed: John Doe etc....." a/c 1 now departs….

Now, back at aircraft 2 (which is usually a spare sitting on the ramp), the part from a/c 1 is installed. This is being done (I think) to make certain that the part in question is indeed bad. Now....when a/c 2 is ops checked on the ground......you guessed it--every thing works (for now). Then, when the spare flies again, 2 legs or so later—DING.....master caution-elev artf feel.

I imagine if all procedures are followed regarding serviceable tags, then QA would have a master record of the individual serial numbers of each and every part installed on each aircraft. Is this usually the case? If so, It would seem that one particular part making its way through the fleet and causing failures and MEL's could be tracked??? Also, what is supposed to happen with the serviceable tags? Do they get sent back to QA to be placed in a master logbook for each aircraft?

 

[pmcustom]

At our repair station, all the important parts are tracked in the computer so you always know what s/n part is on what a/c and in what position, etc...(along with all the dates and other info). A mechanic can swap parts all he wants for troubleshooting, but if he doesn't put everything back the way it was, then you have to write it up. We K-Ball parts all the time, but you can't legally just ignore the bad part, pretend you don't know about it and leave it on the other airplane.

 

[Gatorman]

Whom ever installed the 'defective part' from aircraft #1 into aircraft #2 is indeed inviloation of the FAR for installing a part for not know the 'condition' of that part.

HANDLING OF PARTS

All items or components undergoing maintenance, repairs and/or
alterations in the repair station shall have the component parts
segregated and in containers in order to assure that all parts of the
same unit(s) are kept together. Suitable trays, racks, stands and
protective coverings (as required) are to be provided in shop areas to
ensure maximum protection of all parts. Rejected parts will be
identified by the use of a red reject tag and final disposition will be
the responsibility of the Supervisor - Quality Control.

TAGGING AND IDENTIFICATION OF PARTS

The following is our four (4) tag system:

White tag - Used for identification of unit and customer only. To
be completed by shop supervisor or a designated
employee.

Green tag - Will be attached to units or parts requiring repairs
test and will include work to be performed. To be
executed and signed by inspector only.

Yellow tag - To be attached to completed units which have received
final inspection and are approved for return to
service. The maintenance release is printed or
stamped on the reverse side of this tag. (See
Maintenance Release Statement, Section V,
Page 21). This release will be signed by a designated
person only.

Red tag - Will be attached to rejected parts, pending final
disposition. If rejected parts are in large
quantities, they can be placed in a special container
marked "rejected parts." This tag to be completed by an
inspector.

 

[avbug]

Absolutely this is an improper and illegal practice. No question about it. Installing a known good processor is acceptable, as it was removed functional and tests functional, and is tracable with a known history and operative condition.

Installing the questionable item, especially more than once, is not legal, and puts the company and the pilots in legal jeopardy. The airworthiness certificate of the aircraft has become invalidated per line six, and you may be violated for working on it, dispatching or releasing it, and most certainly for flying it. Especially if you know about the defective part and the problem.

This is poor maintenance practice and sloppy workmanship, not to mention illegal, contrary to good sense and industry standard practice, and a disgrace to both the mechanics doing the work and the company that permits or condones it.

If the part is known to be defective, it needs to be removed from the aircraft and marked, tagged, or destroyed such that it can't be put back in service until repairs have been effective and the part is returned to service.

Various tagging proceedures are used by different repair stations; the system identified by Gator is typical and the most common. None are official and none are regulatory...a part with a yellow tag isn't by nature airworthy, though it may be airworthy...the yellow tag doesn't make it so.

The bottom line is that if the processor as removed doesn't conform to fully operational status in accordance with relevant approved data, then it's nor an airworthy part, and putting it on an aircraft and releasing the aircraft as airworthy is a violation for the company and the mechanic...and the pilot who flies it. Remember that a mechanic may approve a part or aircraft for return to service, but it's the pilot who actually returns it to service...and who therefore accepts ultimate responsibility as both the person returning it to service, a PIC or SIC, and an operator with co-responsibility alongside the company.

Don't fly unairworthy parts.

 

[kcab]

Unfortunately this is the sort of thing that begins to happen when 'market forces' (as they like to call them) put a carrier in a position where they are pressured to cut costs in order to compete. The way it happens usually involves a manager because managers are typically the type that aren't satisfied being (or able to be) a good technician and are more concerned with their 'status' in the heirarchy of the corporate jungle. So they will, for the good of the company and their status within it, take chances that shouldn't be taken.

In the example above it's very much like paying your credit card bill with a cash advance from another credit card.

Not a good sign....