Date: 201603
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Mission: Passenger
Flight phase: Parked
Aircraft component: GPWS
Component problem: Design
Reporter organization: Air Carrier
Reporter qualification: Maintenance Repairman
Human factors: Communication Breakdown; Time Pressure
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Maintenance
Contributing factors: Manuals
Primary problem: Manuals

Narrative: I and a new trainee were working a deferred maintenance item on the Enhanced Ground Proximity Warning System (EGPWS). I was demonstrating how to troubleshoot the EGPWS while also following the tech data. In doing so; it was evident that the Enhanced Ground Proximity Warning Computer needed to be replaced. I demonstrated how to order the correct part for that particular aircraft; and after doing so we installed the new part. Unfortunately; upon installation of the new part; it became immediately evident that the new part was bad from stock. That new part was the only part number of its kind in stock.So after this moment; I informed the Supervisor on the shift of the predicament; and also; suggested that we rob the same (effective) part from a plane that was not scheduled to fly-- due to it being down for an assortment modifications. The supervisor agreed that I should get the part from the other plane. I created a write up to remove the part from that aircraft for use on the aircraft I was repairing. I went to remove the part; and was headed to the inspection office to complete the paperwork process before performing the installation on the aircraft we were working. As I (and the trainee) were headed back to the office; I got a brief message from a mechanic in the hangar who the supervisor had sent to tell me that 'there indeed was an effective part in stock'-- besides the one I had robbed from the hangered aircraft. I went in and talked to the supervisor; he told me to order the other effective part instead of completing the paperwork for robbing the part from the hangered aircraft. In that moment; my instincts were telling me that the part was not compatible; and I asserted that the part is not compatible; however; he showed me in the part inventory-- under the effectivity link; that the part in stock was indeed effective for the plane; and told me to order that part and install it on the aircraft.Upon seeing; and believing; the part was effective for aircraft I was working; myself and the trainee; ordered the 'said effective' part from stock and installed it on the aircraft; performed the follow-on maintenance after installation; and did not find any faults with the EGPWS. I did the documentation and that was it. I logged into my email this morning (the day after) and found an email about the EGPWS on the aircraft I worked; and from that I am doing this report. The event occurred because I did not have immediate evidence to challenge that the part was not effective; and believed what an authoritative figure showed me--and insisted to be true via the evidence in the parts inventory; also the plane was a few hours away from departure.Challenge supervision when I'm told to do something that I have strong instincts about in terms of performing maintenance; disregard departure time of an aircraft; and research part effectivity further in moments that warrant such action; and finally do not believe everything I see in the parts inventory; make sure that I have more than one method of providing evidence of a part being effective for a certain aircraft.




Synopsis: On a CRJ-700; an incompatible Ground Proximity Warning System (EGPWS) was installed because the parts manual was not correct as to the compatibility of the EGPWS for this aircraft.