Date: 201511
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Flight conditions: VMC
Weather elements / visibility: Turbulence; Windshear
Light: Daylight
Aircraft: Gulfstream IV / G350 / G450
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Reverser Lockout
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Human factors: Training / Qualification; Confusion
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Other On Takeoff
Result: Flight Crew Executed Go Around / Missed Approach; Flight Crew Returned To Departure Airport; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Chart Or Publication; Procedure; Human Factors
Primary problem: Human Factors

Narrative: The aircraft experienced a loss of power from the left engine due to a pinned Thrust Reverser (TR). It was determined by Maintenance that the engine FADEC/Electronic Engine Controller (EEC) was sending information to a bad Modular Avionics Unit (MAU) Card.

Callback: Reporter stated the loss of left engine power occurred on takeoff; but there were several factors that contributed to the situation prior to takeoff. Maintenance and Engineering had been monitoring the aircraft's Rolls Royce Tays Turbofan engines and interrogated the onboard maintenance diagnostic computer; but Engineering was not able to determine what the codes being displayed represented. Engineering consulted with a Rolls Royce representative who recommended the hydraulically powered thrust reverser be pinned (locked out). However; installing the lock-out pins in the thrust reversers required the threaded pins to be installed and then backed-out enough to 'not' show an overstow condition.Reporter stated that Maintenance apparently did not understand or did not read that part of the reverser pin installation procedure. As a result; the improperly installed lock-out pins caused the reverser position sensing to indicate the reverser was not stowed; even though the Circuit Breakers (CB) were opened and collared. The Input/Output (I/O) card in the Modular Avionics Unit (MAU) responsible for talking with other aircraft system computers was also malfunctioning; causing the left engine power to roll-back on takeoff. The FADEC Electronic Engine Controller (EEC) was found to be operating correctly. No Crew Alerting Messages (CAS) appeared.

Second narrative: [Report Narrative Contained No Additional Information]


Synopsis: Captain and First Officer reported the Gulfstream G450 aircraft experienced a left engine power rollback on takeoff. A malfunctioning Modular Avionics Unit (MAU) Card and improperly installed reverser lock-out pin contributed to the event.