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Safety Recommendation Details

Safety Recommendation A-92-021
Details
Synopsis: ON FEBRUARY 24, 1989, UNITED AIRLINES FLIGHT 811, A BOEING 747-122 (B-747), N4713U, WAS OPERATING AS A REGULARLY SCHEDULED FLIGHT FROM LOS ANGELES, CALIFORNIA, TO SYDNEY, AUSTRALIA, WITH INTERMEDIATE STOPS IN HONOLULU, HAWAII, AND AUCKLAND, NEW ZEALAND. THERE WERE 3 FLIGHT CREWMEMBERS 15 FLIGHT ATTENDANTS AND 337 PASSENGERS ON BOARD THE AIRPLANE. THE FLIGHTCREW'S FIRST INDICATION OF A PROBLEM WAS WHILE THE AIRPLANE WAS CLIMBING BETWEEN 22,000 AND 23,000 FEET AT AN INDICATED AIRSPEED OF 300 KNOTS. THEY HEARD A SOUND, DESCRIBED AS A "THUMP," WHICH SHOOK THE AIRPLANE. THIS SOUND WAS FOLLOWED IMMEDIATELY BY A "TREMENDOUS EXPLOSION." THE AIRPLANE HAD EXPERIENCED AN EXPLOSIVE DECOMPRESSION. POWER WAS LOST FROM THE NOS. 3 AND 4 ENGINES BECAUSE OF DAMAGE FROM FOREIGN OBJECT INGESTION.
Recommendation: THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: REQUIRE THAT THE ELECTRICAL ACTUATING SYSTEMS FOR NONPLUG CARGO DOORS ON TRANSPORT-CATEGORY AIRCRAFT PROVIDE FOR THE REMOVAL OF ALL ELECTRICAL POWER FROM CIRCUITS ON THE DOOR AFTER CLOSURE (EXCEPT FOR ANY INDICATING CIRCUIT POWER NECESSARY TO PROVIDE POSITIVE INDICATION THAT THE DOOR IS PROPERLY LATCHED AND LOCKED) TO ELIMINATE THE POSSIBILITY OF UNCOMMANDED ACTUATOR MOVEMENTS CAUSED BY WIRING SHORT CIRCUITS.
Original recommendation transmittal letter: PDF
Overall Status: Closed - Acceptable Alternate Action
Mode: Aviation
Location: HONOLULU, HI, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: DCA89MA027
Accident Reports: Explosive Decompression - Loss of Cargo Door in Flight, United Airlines Flight 811 Boeing 747-122, N4713U
Report #: AAR-92-02
Accident Date: 2/24/1989
Issue Date: 4/9/1992
Date Closed: 8/10/1993
Addressee(s) and Addressee Status: FAA (Closed - Acceptable Alternate Action)
Keyword(s):

Safety Recommendation History
From: NTSB
To: FAA
Date: 8/10/1993
Response: THE BOARD NOTES THAT DURING THE PAST YEAR THE FAA HAS WORKED WITH & ENCOURAGED THE AIRLINE INDUSTRY IN THE DEVELOPMENT OF NEW METHODS FOR REMOVAL OF ELECTRICAL POWER FROM NONPLUG CARGO DOOR ACTUATING SYSTEMS ON TRANSPORT-CATEGORY AIRCRAFT. FURTHERMORE, THE FAA HAS REVIEWED THE NONPLUG CARGO DOOR CONFIGURATIONS CURRENTLY INSTALLED ON LARGE TRANSPORT-CATEGORY AIRPLANES & FOUND THAT ELECTRICAL POWER IS REMOVED FROM ALL OF THESE DOORS BEFORE THE AIRPLANE LEAVE THE GATE. ADDITIONALLY, ON SOME OF THESE AIRPLANES, ALL ELECTRICAL POWER TO THE DOOR OPERATING CONTROLS IS REMOVED AS SOON AS AN ENGINE IS STARTED & ITS ASSOCIATED GENERATOR IS PLACED ON-LINE. ANY INADVERTENT CHANGE IN THE POSITION OF THE DOOR LOCK MECHANISMS THAT OCCURRED BEFORE THE REMOVAL OF ELECTRICAL POWER WOULD BE ANNUNCIATED TO THE FLIGHTCREW. THE REVIEW VERIFIED THAT THE WARNING SYSTEMS ON THE DOORS OF THESE AIRPLANES MEET THE POLICIES CONTAINED IN ADVISORY CIRCULAR 25.783-1. THE BOARD ACCEPTS THE FAA POSITION THAT REMOVAL OF ELECTRICAL POWER FROM DOOR CIRCUITS BEFORE TAXI IN CONJUNCTION WITH REDUNDANT & RELIABLE LOCK POSITION WARNING SYSTEMS AS DESCRIBED IN THE AC MEET THE INTENT OF A-92-21. THUS, A-92-21 IS CLASSIFIED "CLOSED--ACCEPTABLE ALTERNATE ACTION."

From: FAA
To: NTSB
Date: 4/20/1993
Response: THE FAA HAS COMPLETED ITS REVIEW OF THIS RECOMMENDATION AND AGREES WITH THE INTENT. THE FAA HAS EVALUATED THE DOOR DESIGNS OF ALL LARGE TRANSPORT CATEGORY AIRPLANES FOR ISOLATION OF POWER TO THE DOORS DURING FLIGHT. ALL OF THE NONPLUG DOORS ON THESE CATEGORY AIRPLANES HAVE BEEN MODIFIED AS NECESSARY TO ACHIEVE THIS OBJECTIVE. NONPLUG DOORS ALREADY HAVE A SEPARATE POWER SWITCH AT THE DOOR OPERATOR'S STATION THAT REMOVES POWER FROM THE DOOR. SOME SWITCHES OPERATE DIRECTLY WHILE OTHERS, SUCH AS THE POWER SWITCHES ON THE BOEING MODELS 737, 747, AND 767, ARE OPERATED BY THE LOCK HANDLE. THE BOEING MODELS 727 AND 757 HAVE SEPARATE DISARM SWITCHES. ON THE LIGHTER TRANSPORT CATEGORY AIRPLANES, THE OUTWARD OPENING DOORS WITHOUT POWERED LATCHES AND LOCKS DO NOT HAVE THE POTENTIAL SAFETY PROBLEMS ASSOCIATED WITH INADVERTENT OPERATION DUE TO ELECTRICAL SHORTS.

From: NTSB
To: FAA
Date: 8/31/1992
Response: THE SAFETY BOARD BELIEVES THAT BY REQUIRING THAT ALL ELECTRICAL POWER BE REMOVED FROM DOOR ACTUATING CIRCUITS AFTER CLOSURE, THE POSSIBILITY OF UNCOMMANDED ACTUATOR MOVEMENTS CAUSED BY WIRING SHORT CIRCUITS THAT MIGHT OCCUR BETWEEN THE TIME THAT THE DOOR IS CLOSED AND THE TIME THAT THE AIRPLANE TAKES OFF IS ELIMINATED. PENDING FURTHER INFORMATION, THE SAFETY BOARD CLASSIFIES SAFETY RECOMMENDATION A-92-21 AS "OPEN-AWAIT RESPONSE."

From: FAA
To: NTSB
Date: 6/22/1992
Response: THE FAA HAS INITIATED A REVIEW OF ALL OUTWARD OPENING NONPLUG CARGO DOORS ON TRANSPORT CATEGORY AIRPLANES. ONE ASPECT OF THIS REVIEW IS TO VERIFY THAT ALL ELECTRICAL POWER TO THE DOORS (EXCEPT FOR ANY INDICATING CIRCUIT POWER NECESSARY TO PROVIDE POSITIVE INDICATION THAT THE DOOR IS PROPERLY LATCHED AND LOCKED) IS REMOVED IN FLIGHT. THE FAA HAS COMPLETED ITS REVIEW OF THE BOEING MODELS 747, 757, 767, 737, AND 727 AND CONCLUDED THAT THE POWER IS REMOVED FROM THE DOORS IN FLIGHT. CONSEQUENTLY, THE FAA DOES NOT PLAN TO INITIATE MANDATORY ACTION ON THESE MODELS.