Event Details

Title:Uncontained engine failure, American Airlines, Inc., Boeing 747-121, N743PA, San Francisco, California, September 18, 1970
Micro summary:This Boeing 747-121 experienced an uncontained engine failure of the #1 engine on climbout.
Event Time:1970-09-18 at 0851 PDT
File Name:1970-09-18-US.pdf
Publishing Agency:National Transportation Safety Board (NTSB)
Publishing Country:USA
Report number:NTSB-AAR-71-7
Site of event:Climb, 525' MSL
Departure:San Francisco International Airport, San Francisco, California, USA
Destination:John F. Kennedy International Airport, New York, USA
Airplane Type(s):Boeing 747-121
Flight Phase:Takeoff
Operator(s):American Airlines
Type of flight:Revenue
Serious Injuries:0
Other Injuries:0
Executive Summary:American Airlines Flight 14, a Boeing 747-121, N743PA, was a scheduled passenger nonstop flight which originated at San Francisco International Airport at 0830 PDT on September 18, 1970. Its destination was New York, John F. Kennedy International Airport. At departure from San Francisco, 105 revenue passengers, 12 nonrevenue passengers, and a crew of 15 were aboard the flight.

The flight's departure from the gate was routine with the exception of some difficulties in starting with No. 1 engine. The airplane was cleared for takeoff from San Francisco's International Airport, Runway 1-R, at 0851. During the takeoff, it was necessary for the flight engineer to reduce power on the No. 1 engine by .10 EPR in order to maintain the EGT within limits. Approximately 16 seconds after lift-off at an altitude of 525 feet m.s.l., the No. 1 engine sustained a separation of the second-stage turbine disk rim. The turbine blades and rim fragments penetrated the high-pressure turbine (HPT) case, engine cowling, and adjacent airplane structure. All fluid lines, electrical cables, and pneumatic ducts located in the pylon area were severed, and an intense fire ensued. Two fuel tank access plates on the bottom of the wing inboard of No. 1 pylon were also penetrated by turbine fragments.

The fire warning for the No. 1 engine came on simultaneously with the engine explosion. Emergency fire control procedures were initiated and executed. The fire, which was observed by the captain, was propagating over the top of the left wing and lasted approximately 3 minutes. As a result of complete failure of the No. 1 hydraulic system, alternate extension of the body main landing gear, nose landing gear, and inboard trailing edge flaps was necessary. A successful landing was accomplished on San Francisco's International Airport. Passengers and crewmembers were deplaned on the taxiway by means of boarding steps. There were no injuries to passengers, crewmembers, or persons on the ground.

The National Transportation Safety Board determines that the probable cause of this incident was a progressive failure in the high-pressure turbine module in the No. 1 JT9D-3A engine. This failure was initiated by the undetected stress rupture fractures of several first-stage turbine blades and culminated in the inflight separation of the second-stage turbine disk rim.

The Safety Board sent a letter to the Federal Aviation Administration (FAA) on September 25, 1970. This letter related some of the problem areas associated with JT9D engine operations at higher than desirable turbine temperatures and made recommendations toward correction of these conditions.

The Administrator's response dated October 1, 1970, indicated that appropriate action had been taken regarding most of the Board's recommendations and that the remaining items were being evaluated. The Administrator's additional response dated December 23, 1970, indicated that further action had been taken to resolve the problems.
Learning Keywords:Systems - Engine - Uncontained Engine Failure
Systems - Flight Control System
Systems - Hydraulics
Systems - Landing Gear
Consequence - Damage - Airframe or fuselage


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