Serious incident McDonnell Douglas DC-9-31 N956VJ, Monday 6 August 1984

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Date:	Monday 6 August 1984
Time:	13:05 LT
Type:	McDonnell Douglas DC-9-31
Owner/operator:	USAir
Registration:	N956VJ
MSN:	47588/699
Engine model:	P&W JT8D-7B
Fatalities:	Fatalities: 0 / Occupants: 85
Other fatalities:	0
Aircraft damage:	Minor
Category:	Serious incident
Location:	Nashville, TN - United States of America
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	Nashville, TN (KBNA)
Destination airport:	Pittsburgh International Airport, PA (PIT/KPIT)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
DURING THE CLIMB-OUT, A 15% DECREASE IN THE RIGHT ENG EPR WAS NOTED BY THE FLT CREW. THIS WAS FOLLOWED BY A LOUD BANG & FAILURE OF THE #2 ENG. THE #2 ENG WAS SHUT DOWN & THE ACFT WAS FLOWN BACK TO THE DEPARTURE ARPT. AN INITIAL EXAM REVEALED THAT THE RIGHT ENG TOP COWLING HAD SEPARATED & THE LOWER SECTION OF THE COMBUSTION CASE WAS SPLIT. ENG REMOVAL & TEARDOWN REVEALED THE #5 FUEL NOZZLE NUT LOCK RING WAS MIS-ASSEMBLED. THIS DETRACTED FROM THE TORQUE ON THE FUEL NOZZLE NUT & INADEQUATELY COMPRESSED THE #5 FUEL NOZZLE SEAL. SUBSEQUENTLY, THE FUEL NOZZLE LEAKED & ALLOWED LOCAL OVERTEMP OF THE OUTER COMBUSTION CHAMBER CASE AT THE 6 O'CLOCK POSITION.

Probable Cause:

Accident investigation: