Bizarre and Foolish ends in Tragedy - 1973

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GAHorn
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Bizarre and Foolish ends in Tragedy - 1973

Post by GAHorn »

From the Web:
Have you ever flown a DC-10 at 39,000 feet with 115 passengers on board and been tempted to experiment with autothrottle system - just to see what would happen? In late 1973, a pair of curious National Airlines pilots did and their actions nearly cost everyone on board their lives.

On November 3, 1973, National Airlines Flight 27 was operating as a scheduled passenger flight between Miami and San Francisco with intermediate stops at New Orleans, Houston, and Las Vegas. At about 4:40 p.m., while the aircraft was cruising at 39,000 feet 65 miles southwest of Albuquerque, the No. 3 engine fan assembly disintegrated and its fragments penetrated the fuselage, the Nos. 1 and 2 engine nacelles (which contain those engines), and the right wing area. The resultant damage caused decompression of the aircraft cabin and the loss of certain electrical and hydraulic services.

The flight crew initiated an emergency descent, and the aircraft was landed safely at Albuquerque International Airport 19 minutes after the engine failed. The 115 passengers and 12 crewmembers exited the aircraft by using the emergency slides.

As a result of the accident, one passenger died and 24 persons were treated for smoke inhalation, ear problems, and minor abrasions.

The National Transportation Safety Board determined the probable cause of this accident was the disintegration of the No. 3 engine fan assembly as a result of an interaction between the fan blade tips and the fan case. The fan-tip rub condition was caused by the acceleration of the engine to an abnormally high fan speed which initiated a multiwave, vibratory resonance within the fan section of the engine. The precise reason or reasons for the acceleration and the onset of the destructive vibration could not be determined conclusively.

However, it is clear that the captain and flight engineer's irresponsible actions were to blame. They were experimenting with the autothrottle system, which supplied the instruments that measure the rotational speed of each engine's low pressure compressor. The cockpit voice recording contains the following conversation just prior to the number 3 engine exploding:

Flight Engineer: "Wonder, wonder if you pull the N1 tach will that, -- autothrottle respond to N1?"
Captain: "Gee, I don't know."
Flight Engineer: "You want to try it and see?"
Captain William Brookes, who had been a National Airlines pilot since 1946 and who should have known better responds, "Yeah, let's see here."
Flight Engineer: "You're on speed right now though."
Captain: "Yeah."
Flight Engineer: "You know what I mean if your annunciated speed - if you got, ---"
Captain: "Still got 'em."
Flight Engineer: "Well - - haven't got it -"
Captain: "There it is."
Flight Engineer: "I guess it does."
Captain: "Yeah, I guess it does - right on the nose."

[At the instant he says the word "nose" there is the sound of the number 3 engine exploding followed by ratcheting sounds.]

Captain: "[expletive deleted] what was that?"

By playing with the autothrottle controls - in what amounted to an in-flight failure-analysis test of the autothrottle system - the crew managed to produce a condition where the engines were pushed to higher rotation speeds than they were designed for. According to audio analysis of the CVR tape, all three engines surged (#1 to 105%, #2 to 107% and number 3, which failed, to 110%).

Pieces of the engine fanblades struck the fuselage breaking a window near seat 17H. According to a witness, the occupant of the seat was partially forced through the window opening and was temporarily retained in this position by his seatbelt. Efforts to pull the passenger back into the airplane by another passenger were unsuccessful, and the occupant of seat 17H was subsequently forced entirely through the cabin window.

The New Mexico State Police and local organizations searched extensively for the missing passenger. A computer analysis was made of the possible falling trajectories, which narrowed the search pattern. However, the search effort was unsuccessful, and the body of the passenger was not recovered.
<edit: The body was recovered years later in the desert by a construction crew who happened upon the skeleton.>

The plane made an emergency landing at Albuquerque International Airport. It was repaired and was later flown by Pan Am (as Clipper Meteor) through 1984. It was scrapped in mid-2002.

Source: Original Article By Patrick Mondout Adapted from National Transportation Safety Board (NTSB) report NTSB-AAR-75-2.
'53 B-model N146YS SN:25713
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johneeb
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Re: Bizarre and Foolish ends in Tragedy - 1973

Post by johneeb »

Two words you just don’t want to hear the captain say “watch this”
John E. Barrett
aka. Johneb

Sent from my "Cray Super Computer"
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