B777-200
Maintenance Powerplant; Maintenance Airframe
Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Other / Unknown
General Maintenance Action
Aircraft; Human Factors
I was installing coach passenger seats on a B777-200 aircraft Aft Center Rows XX; YY and ZZ; with a Partner (Mechanic) on November 2012. I was working on the left side [of the Center rows]; Partner on the right. The left side installation went okay. But the right side seat track had debris inside and carpet that came close to edge of the seat track. Seat Row-ZZ was the most difficult to install and required two people install. One person to push on seat to align and the other to tighten shear pin. I was pushing seat into position while partner was tightening shear pin. Shear pin contacted edge of seat track and gave a false indication of applied torque. Seat came loose during a trip and was later fixed at a Line Station. Rows XX and YY were okay and no other problems noted. ETOPS aircraft.
I was working with a fellow Mechanic installing upgraded Economy seats on a B777-200 aircraft in November 2012. I was informed a month later that a Center row seat came loose. I do not know why the seat row came loose even though the other seats that we installed were properly installed and secured. The only thing that I can think of why the seat row came loose is because of the location of the seat; which is in front of the storage container; which made it visually not as clear as the other seats when it comes to visually observing the aft seat track attachment. I would also like to say that after we installed each seat [row]; we not only do a visual [check] to make sure it is secured; but also do a manual test by lifting; pulling and wiggling the back of the seats to determine if there are any discrepancies. When we did the seat row; there was nothing unusual; or out of the ordinary as to compared to the other seat rows. ETOPS aircraft.
Two Maintenance Base mechanics report how a false indication of applied torque to a seat row locking shear pin contributed to a B777-200 coach passenger seat coming loose from a floor track in flight.