Date: 201412
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Gulfstream V / G500 / G550
Operator: Air Taxi
Operating under: Part 135
Mission: Passenger
Flight phase: Parked
Aircraft component: Pneumatic Valve/Bleed Valve
Component problem: Improperly Operated; Malfunctioning
Reporter organization: Air Taxi
Reporter function: Inspector; Lead Technician
Reporter qualification: Maintenance Powerplant; Maintenance Inspection Authority; Maintenance Airframe
Human factors: Confusion; Situational Awareness; Communication Breakdown
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted; General Maintenance Action
Contributing factors: Procedure; Human Factors; Manuals; Chart Or Publication
Primary problem: Human Factors

Narrative: Maintenance was performed on aircraft left hand engine on December 2014. The [Technician] (Tech) performed scheduled maintenance replacing the right igniter on the # 1 engine. I inspected the igniter installation as well as the internal compressor fairing installation. When the Tech completed the close up; I followed up and inspected to verify the engine core access panels as well as pneumatic ducts removed to gain access were installed and secured. I performed post maintenance engine runs and leak checks as required with no discrepancies. [Three days later]; the aircraft experienced compressor stalls inflight causing the aircraft to [make] an unscheduled landing at a field other than the intended destination. This was the 3rd flight since this engine maintenance had been performed. After the landing the aircraft was inspected to determine the cause of the compressor stalls. It was determined that the HPC stage-5 air non-return valve was installed incorrectly on the left hand engine. This was corrected; engine inspections were accomplished and the aircraft was returned to service [two days later.]This valve was removed as part of the duct work removal and is fitted internally where two ducts join; held by a single clamp. The removal of the ducts is an 'as needed' item in the procedure for the scheduled igniter maintenance check. The technician reinstalled the valve incorrectly after the inspection was completed and with the duct work installed; I was unable to see the valve was installed incorrectly. The valve is a smaller diameter than the duct and can easily be installed reversed. The technician failed to refer to maintenance manual for proper installation procedures. In addition; I considered this a follow up procedure to gain access as needed and felt that after the inspection of the igniter installation; a follow up inspection of the close up was sufficient. Additionally while this tech has limited experience on this aircraft; he has over 30 years experience working similar equipment and systems. All the revised aircraft and engine maintenance manuals were made available.I feel that the technician's complacency and lack of awareness during the removal and replacement procedures caused him to install the valve incorrectly. I was handling other; more critical; engine inspections on this aircraft and trusted the techs experience to install the ducts. I also feel the [Maintenance] Manual does not address the direction of the valve installation. Depending on power settings and aircraft stage of flight; an incorrect installation of this valve will cause compressor stalls which will in turn cause loss of power. I feel that makes this a critical installation and the Aircraft Maintenance Manual (AMM) should have a note to address the directional installation of the valve. I was aware there was an issue with the engine and was notified [approximately twenty days later] by the aircrafts' Chief Inspector of their finding and a request for us to investigate. Our Chief Inspector is reviewing the incident. He met with the local FSDO to make them aware of this occurrence and he will present his plan of action to the required parties when completed. The removal and replacement of the igniter plug references the removal of the ducts.




Synopsis: An Aircraft Maintenance Inspector reports a Gulfstream G-V aircraft experienced Left engine compressor stalls inflight; requiring an unscheduled landing at a field other than the intended destination. A High Pressure Compressor (HPC) Stage-5 Bleed air Non-Return Valve was installed in reverse on the Rolls Royce BR710 engine. Maintenance Manual did not address the valve's air flow direction during installation.