Eurocopter AS 350/355/EC130 - Astar/Twinstar/Ecureuil
Maintenance Airframe; Maintenance Powerplant
Situational Awareness; Confusion; Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Maintenance Action
Aircraft; Human Factors; Procedure
[I was] performing scheduled maintenance. Airworthiness Directive (AD) required on Hydro Mechanical Units (HMU) on Number 1 and Number 2 Engines; which required removal of HMUs and several cannon plugs. [I] complied with AD and other maintenance. [I] installed HMUs. Other technicians (four) checked-over work performed and checked HMUs for correct installation and Foreign Object Debris (FOD). Pilot performed a detailed preflight to check for FOD. [I] prepped aircraft for a ground run/leak check to check operation of HMUs. [I] applied power and 'Caution FLI/No Tq' indication on Number 2 Engine side. [All] four Technicians removed cannon plugs; cleaned and reinstalled. [I] applied power with no caution. [I] performed successful ground run. [I] performed a check flight; while landing at Base; same cautions appeared. Removed cannon plugs and torque (Tq) pickup; cleaned reinstalled; ground run OK. Check flight OK. Training performed 1.5 check ride with no cautions. Several times aircraft is run and positioned on dolly for bad weather; no problems. I am off on my scheduled days; will cover for Mechanic Y [when I return]. Go to aircraft to troubleshoot and meet Engine Manufacturer Technical Representative and Mechanic Z. After several hours troubleshooting; I look at #2 Engine for the 3rd time and notice that a cannon plug to the Stepper Motor (hard to see); (a hard line and two other sensors and cannon plugs are over top of this); is not seated all the way. [I] managed to get it secured all the way. Applied power and all systems are normal; No 'Cautions.' [I] checked Number 1 Engine for exceedances. Aircraft released for return to service. Was told this has happened on another occasion with same results. [Recommend] better lighting; removal of cowlings; fire walls and etc.; to get a better look; bigger mirrors.
After engine ground runs; flight checks and several hours of troubleshooting for a recurring Caution FLI/No Tq (torque) indication on a Eurocopter helicopter; an Aircraft Maintenance Technician (AMT) notices a cannon plug to the Stepper Motor on Number 2 Engine was not seated all the way. Same issue happened before with same results.