Pertinent to
TWA800?
747 CARGO DOORS THAT OPEN MYSTERIOUSLY
The story below is very very scary knowing what we know about forward cargo doors opening in flight from electrical causes. If that CB had been pushed in (why was it out?) during flight, that forward cargo door would have ruptured/opened with known catastrophic results. What is a 'controller' and what 'malfunctioned'?
UAL, above incident airline and well familiar with UAL 811, had habit of pulling door CB out and were told to stop, order 8300.10 below. They are apparently still pulling the door CB and it may have saved their ass.
Please use whatever influence you have in safety to pursue the shorted wiring/forward cargo door rupture/explosive decompression/inflight break-up explanation for 747 accidents. Do something.
Sincerely,
Barry
Difficulty Date : 10/11/00
Operator Type : Air Carrier
ATA Code : 5210
Part Name : CONTROLLER
Aircraft Manufacturer : BOEING
Aircraft Group : 747
Aircraft Model : 747-422
Engine Manufacturer : PWA
Engine Group : 4056
Engine Model : PW4056
Part/Defect Location : CARGO DOOR
Part Condition : MALFUNCTIONED
Submitter Code : Carrier
Operator Desig. : UALA
Precautionary Procedure : NONE
Nature : OTHER
Stage of Flight : INSP/MAINT
District Office Region : Western/Pacific US office #29
A/C N Number : 199UA
Aircraft Serial No. : 28717
Discrepancy/Corrective Action: FWD CARGO DOOR OPENED
BY ITSELF WHEN CB PUSHED IN. 
ON ARRIVAL, CIRCUIT BREAKERS WERE PUSHED IN, WHEN PRESSURE RELIEF DOOR HANDLE WAS OPENED THE DOOR LATCHES OPENED AND THEN THE DOOR OPENED ON ITS OWN. COULD NOT DUPLICATE PROBLEM AFTER INITIAL OPENING.
APPENDIX: 4
BULLETIN TYPE: Flight Standards Information Bulletin (FSIB)
for Airworthiness (FSAW)
BULLETIN NUMBER: FSAW 93-50
BULLETIN TITLE: Inappropriate Use of Circuit Breakers
During B-747 Lower Lobe Cargo Door Operation
EFFECTIVE DATE: 06-02-94
---------------------------------------------------------------
1. SUBJECT. This FSIB informs inspectors of unsafe procedures being used by some operators to close and lock the lower lobe cargo doors of the Boeing 747 (B-747) series aircraft.
2. BACKGROUND.
A. This bulletin was developed after an inquiry by a foreign airworthiness authority into the special procedures used by a specific operator to close and lock the lower lobe cargo doors of B-747 series aircraft. The special procedure included in the operator's maintenance manual called for manual tripping of the cargo door control circuit breakers and the section 2 ground handling bus circuit breaker in order to further remove the possibility of power being applied accidentally to the cargo door control circuitry.
B. The manual tripping of the circuit breakers in special cargo door lock procedures is unnecessary and decreases the reliability of the circuit breakers to perform their intended function.
Frequent switching of the breakers could cause them to trip before the point of rated voltage or not to trip at all. Both cases could have adverse effects (such as the following) in relation to the safe operation of the cargo doors:
(1) Circuit breakers that trip before the point of rated voltage would cause increased manual operation of the cargo doors.
(2) Manual operation could introduce additional failure conditions, such as out-of-sequence operation and overdriving of the cargo door mechanisms.
(3) Service history has shown that manual operation of the cargo doors is more prone to cause damage; for example, the failure of a breaker to trip at the point of rated voltage could lead to failed components and fire.
2 C. The revision to the B-747 cargo door lock sectors warning system, in airplanes compliant with Airworthiness Directive (AD)90-09-06, provides an increased level of integrity so that manual tripping of the circuit breakers is not necessary to prevent the possibility of an uncommanded opening of the cargo doors.
Furthermore, power to the cargo door is automatically removed by the Master Latch Lock System upon first motion of the Master Latch Lock Switch away from the fully unlocked position.
3. ACTION. Principal maintenance inspectors (PMI) having certificate management responsibilities for operators of Boeing 747 series aircraft should ensure that this information is brought to the attention of their respective operators. Any operators using this procedure should be discouraged from its continued use.
4. INQUIRIES. This FSIB was developed by SEA.AEG. Any questions regarding this information should be directed to AFS-510 at (703) 661-0333, extension 5018.
5. EXPIRATION. This FSIB will expire on 05-31-95.
/s/ Edgar C. Fell
Another case in point
Difficulty Date : 6/10/00
Operator Type : Air Carrier
ATA Code : 2400
Part Name : HARNESS
Aircraft Manufacturer : BOEING
Aircraft Group : 747
Aircraft Model : 747212B
Part/Defect Location : FUSELAGE
Part Condition : ARCED
Submitter Code : Carrier
Operator Desig. : IPXA
Precautionary Procedure : NONE
Nature : OTHER
Stage of Flight : INSP/MAINT
District Office Region : Southern US office #01
A/C N Number : 521UP
Aircraft Serial No. : 21944
Discrepancy/Corrective Action: INSPECTION TYPE: C, FWD CARGO HOLD -
CABLE LOOM PASSING THROUGH FRAME AT BS 520, RBL 24 SHOWS EVIDENCE OF ARCING. ACCOMPLISHED PER QUERY NOTE 35/2000 WHICH ASKS FOR WIRES TO BE REMOVED AS SYSTEM IS INACTIVE. WIRES REMOVED FROM CB C914 IN P14 PANEL TO RELAY R175 IN PANEL P86, AT FWD CARGO DOOR PER WDM 24-51-72.
Difficulty Date : 2/18/01
Operator Type : Air Carrier
ATA Code : 5230
Part Name : DOOR
Aircraft Manufacturer : BOEING
Aircraft Group : 747
Aircraft Model : 747-123F
Part/Defect Location : AFT CARGO DOOR
Part Condition : UNSECURE
Submitter Code : Carrier
Operator Desig. : IPXA
Precautionary Procedure : UNSCHED LANDING
Nature : WARNING INDICATION
Stage of Flight : CLIMB
District Office Region : Southern US office #01
A/C N Number : 672UP
Aircraft Serial No. : 20324
Discrepancy/Corrective Action: INSPECTION TYPE: N/A, ATB-
UNABLE TO PRESSURIZE IN AUTO OR MANUAL MODE AFTER TAKEOFF. A/C PRESSURIZED ON LANDING. *S/D* SECURED AFT LOWER CARGO DOOR LATCH LOCK HANDLE AND VENT DOORS PERFORMED CARGO DOOR TEST, NO FAULTS NOTED.
