EMIL hers is more, and out of 17 pages there were only two incidents of MRO maintenace being inadequte.
NTSB Identification: CHI03IA097.
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier operation of United Airlines Inc (D.B.A. United Airlines)
Incident occurred Tuesday, April 01, 2003 in Chicago, IL
Probable Cause Approval Date: 9/30/2003
Aircraft: Boeing 747-422, registration: N175UA
Injuries: 319 Uninjured.
While in normal cruise flight, the crew experienced lateral control problems. An emergency was declared. The aircraft landed safely at the intended destination. Evidence of a water leak was identified by the cabin crew approximately 5 hours from the destination. Efforts to control the leak were effective, however it was not completely stopped. Water was reported coming from the upper deck and flowing through the main deck ceiling. The flight was subsequently directed by air traffic control to make an enroute course change. However, when this command was entered in the Flight Management Computer (FMC) the aircraft began a shallow left turn instead of a right turn as required. Initial attempts to disconnect the autopilot were not successful and the autopilot was manually overridden. The relief first officer at the controls stated the controls "felt unusual" and "stiff." The captain reported elevator and rudder were normal, but bank angle was limited. The landing was accomplished smoothly and safely according to the captain, and the aircraft was taxied to the gate without incident. After landing, the captain noted the controls felt normal. Ramp personnel reported a significant amount of water draining from the fuselage and the drain masts at the gate. A post-incident examination of the aircraft revealed that areas of the main deck carpeting was saturated. The canted pressure deck overboard drains were not obstructed. A 6-inch long by 0.125-inch wide gap was located along the outboard edge of the canted pressure bulkhead on the right side of the aircraft. The seam was not sealed as required. Immediately aft of the canted pressure bulkhead were aileron and flight spoiler control cables. Four (4) circuit breakers common to the external drain line heaters were found open. The external drain lines route wastewater from the cabin overboard. The breakers were pulled in conjunction with routine cleaning of the drain lines prior to departure. Ground functional testing of the aileron controls, the aileron trim and the autopilot did not find any anomalies. A flight test was completed to verify in-flight operation of the flight controls and potable water system. No anomalies were noted. Airline procedures related to the routine inspection and cleaning of the external drains were reviewed. Resetting of the drain heater circuit breakers was the last item. A service bulletin had been issued which recommended testing, cleaning and inspection of the canted pressure deck drainage system (overboard drains), general visual inspection of the deck structure a pressurization test. Service bulletin instructions included a visual inspection for loose, missing or cracked sealant. The airline was in the process of incorporating the service bulletin into its maintenance program. As a result, the initial service bulletin procedures had not been completed prior to the incident. An airworthiness directive (AD) which required cleaning of "the cavity aft of the wing center section" and verification that all drains were open and clean was in effect at the time of the incident and had been complied with. A new AD was issued following the incident which mandated full compliance with the existing service bulletin.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
Failure of company maintenance personnel to fully comply with published maintenance/inspection procedures, as well as the resulting inoperative drain heaters and restricted movement of the aileron control cables. Contributing factors were the impeded waste water drain system due to the inoperative heaters and the reduced aileron control due to restricted movement of the control cables.
NTSB Identification: CHI00IA018.
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier (D.B.A. United Airlines)
Incident occurred Thursday, October 28, 1999 in CHICAGO, IL
Probable Cause Approval Date: 6/3/2002
Aircraft: Boeing 757-222, registration: N575UA
Injuries: 68 Uninjured.
The pilot reported, "We encountered substantial vertical control flutter FL310-350 .78-.80 Mach with left, center, right autopilot and no autopilot. Flutter stopped when IAS was decreased. Descended to FL310, 250 kts., .75 Mach and had no more flutter. The flight diverted to O'Hare Airport and made an uneventful landing. Maintenance inspections revealed excessive free play in the elevator flight controls. The allowable limit is 0.340 inch and 0.50 inch was measured. The free play was corrected in accordance with the current maintenance manual. The bushings, the left center power control actuator (PCA), two reaction links, and four ilder links were replaced. During a subsequent test flight, vertical oscillations were still present. Further maintenance action included replacing all elevator hinge bearings and four PCA's. The third flight test was successful and the airplane was returned to service. Inspection of two reaction link rod ends revealed axial and radial wear which exceeded allowable limits. Inspection of the 16 hinge bearings revealed 3 bearings had axial and radial wear which exceeded limits and had moderate to severe corrosion. On October 11, 2001, the FAA issued Airworthiness Directive (AD) 2001-20-11 that was applicable to all B-757 series airplanes to "prevent unacceptable airframe vibration during flight, which could lead to excessive wear of elevator bearings and result in reduced controllability of the airplane…" The AD required, "Before further flight after the free-play checks, lubricate the bearings in the elevator PCA load loop and hinge line." Lubrication of the hinge bearings had not been required in a previous AD. The new AD required recurrent inspections every 18 months instead of the previous requirement of 4,000 hours, or 3,000 hours for some models. On January 28, 2001, Boeing issued a maintenance manual revision that corrected improper instructions for elevator free-play checks. The improper procedures in the maintenance manual had been in effect from September 20, 1997, to January 28, 2001.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
the in-flight vibration of the airplane's elevator due to excessive freeplay in the elevator control system. Factors included the corrosion of the elevator PCA reaction link bearings and the elevator hinge bearings, excessive axial and radial wear of the elevator PCA reaction link bearings, the inadequate procedures for lubricating the elevator hinge bearings, and the incorrect procedures for measuring elevator free play.
NTSB Identification: FTW98IA019 .
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier UNITED AIRLINES, INC.
Incident occurred Thursday, October 16, 1997 in SEATTLE, WA
Probable Cause Approval Date: 5/4/1998
Aircraft: Boeing 757-222, registration: N581UA
Injuries: 196 Uninjured.
As the airplane was rotated for liftoff from Seattle, the captain noticed that the EICAS (engine indication and crew alerting system) 'EMERGENCY DOOR' light had illuminated. According to the Airplane Fight Manual, if pressurization is normal (and it was), the crew need not take further action. During the descent for landing, a flight attendant said she heard a loud noise from the left side of the airplane. The airplane landed uneventfully at Denver. Inspection disclosed the left off-wing slide had separated from the airplane, causing minor damage to the access door, flap, and fuselage skin. The slide had been routinely replaced the previous evening by a mechanic using a flashlight and referencing the airplane maintenance manuals. After installing the slide, the mechanic closed the panel and placed the actuator handle in the horizontal position (as per instructions placarded on the maintenance access door). He said he had never received any training for installing the off-wing slide. There have been four similar incidents since the airplane entered commercial service, prompting the manufacturer to issue Service Bulletin (S.B.) 757-25-0182.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
Maintenance personnel's failure to properly secure the left off-wing slide door after routine slide replacement, allowing an inflight separation of the slide. Factors were inadequate training of maintenance personnel and inadequate written instructions by the airplane manufacturer.
NTSB Identification: CHI97IA117 .
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier UNITED AIRLINES
Incident occurred Monday, April 28, 1997 in CHICAGO, IL
Probable Cause Approval Date: 6/26/1998
Aircraft: Boeing 737-200, registration: N9063U
Injuries: 2 Minor, 56 Uninjured.
The airplane experienced an uncontained failure of the 10th stage compressor disk in the right engine. The flight crew aborted the takeoff, and an emergency evacuation was conducted after an engine fire was reported to the flight crew. Metallurgical inspection of the disk revealed that it had received insufficient nickel plating when it was reworked at the operator's facility 38 flight hours and 33 cycles prior to the incident. This resulted in cadmium embrittlement of the steel. The investigation revealed the operator had no written procedures to outline the process parameters and rectifier set-ups to be used during the NiCad plating process. NiCad plating line personnel also did not have any means of checking the thickness of the nickel plating during the plating process.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
inadequate nickel plating was applied to the compressor disk during the rework process at the operator's overhaul facility, which resulted in a brittle fracture in the disk and an uncontained engine failure. A factor was the operator's lack of written procedures and guidance for personnel on the NiCad plating line, along with their failure to supply a method of measuring the thickness of nickel applied.
NTSB Identification: CHI95IA119 .
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier operation of (D.B.A. UNITED AIR LINES )
Incident occurred Friday, April 07, 1995 in CHICAGO, IL
Probable Cause Approval Date: 7/11/1996
Aircraft: BOEING 737-222, registration: N9090U
Injuries: 116 Uninjured.
THE LEFT OUTBOARD MAIN WHEEL SEPARATED FROM THE AIRPLANE ON TAKEOFF. THE AIRPLANE WAS LANDED WITHOUT FURTHER INCIDENT. INVESTIGATION REVEALED THAT THE OUTER BEARING FAILED. HEAT AND MECHANICAL DAMAGE WERE CONSISTENT WITH INADEQUATE LUBRICATION. PRE-EXISTING MECHANICAL DAMAGE COULD NOT BE DETERMINED. THE WHEEL BEARING HAD ACCUMULATED 349 LANDING CYCLES SINCE INITIAL INSTALLATION, AND 219 CYCLES SINCE A BRAKE CHANGE. IT COULD NOT BE CONFIRMED THAT THE BEARING HAD BEEN REPACKED WITH GREASE SINCE INITIAL INSTALLATION. AN UNKNOWN QUANTITY OF GREASE HAD MIGRATED AWAY FROM THE BEARING CAVITY DURING OPERATION. AVERAGE CYCLES BETWEEN 737-200 WHEEL CHANGES PERFORMED BY THE OPERATOR WERE 259, AND WORLDWIDE ACCORDING TO BOEING WERE 200. AN OPTIONAL OUTER GREASE SEAL TO RETAIN GREASE WITHIN THE BEARING WAS NOT INSTALLED. THE BEARING AND WHEEL ASSEMBLY MANUFACTURERS STATED THAT AFTER 150 CYCLES, LUBRICATION PROPERTIES OF GREASE RAPIDLY DEGRADE.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
the inadequacy or deterioration of lubricating grease in the wheel bearing, which led to the total bearing failure and subsequent loss of the wheel. Factors were the insufficiently defined procedures for repacking the bearing, along with an insufficient method of retaining lubricant within the bearing.
NTSB Identification: LAX93IA245 .
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Incident occurred Tuesday, June 08, 1993 in LOS ANGELES, CA
Probable Cause Approval Date: 8/1/1994
Aircraft: BOEING 757-222, registration: N540UA
Injuries: 197 Uninjured.
The aircraft was climbing through 25,000 feet in light turbulence when the crew felt two jolts and heard a loud explosive noise followed by a sharp roll to the left. A visual inspection revealed that the left overwing emergency escape slide deployed and separated in flight. The crew returned to Los Angeles and made an uneventful landing. Post incident examination revealed that the slide compartment door was unlatched and open, and, the adjacent maintenance access door was open, with the latching handle in the unlocked position. The flight prior to the incident one had experienced two EICAS warning messages concerning the left overwing slide door. After landing, maintenance personnel accessed the compartment, cleaned a proximity switch then functionally tested the system. The flight was then dispatched with no open items. The maintenance closing procedure in effect at the time of the incident called for one mechanic to hold the bottom corners of the 33 inch wide slide door closed while manipulating the latching handle in a maintenance access door 12 inches aft of the slide door. The procedure has since been changed to require two mechanics, one to hold the door closed while the second manipulates the latching handle.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
the inadvertent deployment of an overwing emergency excape slide due to the inadequate latching of the slide compartment door following access by maintenance personnel. A factor in the accident was the inadequate door closing procedure specified by the manufacturer and the airline in the maintenance instructions.
NTSB Identification: MIA92IA166 .
The docket is stored on NTSB microfiche number 47619.
Nonscheduled 14 CFR Part 121: Air Carrier operation of UNITED PARCEL SERVICE CO.
Incident occurred Friday, August 21, 1992 in MIAMI, FL
Probable Cause Approval Date: 8/29/1994
Aircraft: DOUGLAS DC-8-71F, registration: N748UP
Injuries: 3 Uninjured.
AIRCRAFT EXPERIENCED COLLAPSE OF THE LEFT MAIN LANDING GEAR BOGIE WHILE STOPPED AT THE RUNWAY AWAITING TAKEOFF CLEARANCE. POSTINCIDENT EXAMINATION INDICATED THE AFT BOGIE SWIVEL JOINT LUGS HAD FAILED DUE TO STRESS CORROSION CRACKING. THE SWIVEL JOINT DID NOT HAVE PROPER LUBRICATION WHICH KEEPS WATER OUT. THIS ALLOWED FORMATION OF CORROSION ON THE SURFACE OF THE LUGS, AND SUBSEQUENT CRACK INITIATION AT THE CORROSION PITS. OPERATOR MAINTENANCE REQUIREMENTS SPECIFIED THAT THE SWIVEL JOINT BE LUBRICATED EVERY WEEKEND CHECK AND EVERY 'A' CHECK. THE WORK CARDS FOR THESE TWO INSPECTIONS CALLED OUT IN NARRATIVE FORM THE LUBRICATING OF THE BOGIE PIVOT JOINT. THE CARDS CALLED FOR THE SWIVEL JOINT TO BE LUBRICATED BY REFERENCE TO A NUMBER ON AN ILLUSTRATION. THE FAILURE OF THE SWIVEL JOINT LUGS WAS THE SUBJECT OF DOUGLAS AIRCRAFT ALL OPERATOR LETTERS IN 1976 AND 1990. THESE LETTERS STRESSED TO OPERATORS THE IMPORTANCE OF LUBRICATING THE SWIVEL JOINT TO PREVENT CORROSION FORMATION.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
FAILURE OF THE AIRCRAFT OPERATOR MAINTENANCE PERSONNEL TO ADEQUATELY LUBRICATE AND SEAL THE MAIN LANDING GEAR BOGIE BEAM SWIVEL JOINT AS REQUIRED BY MANUFACTURER AND OPERATOR MAINTENANCE PROGRAM REQUIREMENTS. THIS ALLOWED MOISTURE TO ENTER THE SWIVEL JOINT AND CAUSE CORROSION DAMAGE WHICH CAUSED STRESS CORROSION CRACKING AND FAILURE OF THE SWIVEL JOINT LUGS. CONTRIBUTING TO THE INCIDENT WAS LACK OF CLEAR INSTRUCTIONS IN THE OPERATORS MAINTENANCE PROGRAM REGARDING LUBRICATION OF THE SWIVEL JOINT.
NTSB Identification: LAX92IA027 .
The docket is stored on NTSB microfiche number 46059.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Incident occurred Monday, October 28, 1991 in LAS VEGAS, NV
Probable Cause Approval Date: 5/5/1993
Aircraft: MCDONNELL DOUGLAS DC-10-10, registration: N1820U
Injuries: 179 Uninjured.
WHILE CLIMBING THRU 35,000 FT FOR A CRUISE ALTITUDE OF 37,000 FT, THE CREW HEARD A LOUD 'THUMP' & THE ACFT DEPRESSURIZED. AS THE CREW DESCENDED TO 11,000 FT, THE CABIN ALTITUDE CLIMBED TO 30,000 FT. THE FLT DIVERTED TO A NEARBY ARPT & SAFELY LANDED. EXAM OF THE ACFT DISCLOSED THAT REPETITIVE PRESSURIZATION CYCLES CAUSED THE INITIATION OF A FATIGUE CRACK & THE RESULTANT RUPTURE OF A FORWARD PRESSURE BULKHEAD. OVER 14 YRS EARLIER, DOUGLAS ISSUED SERVICE BULLETINS ADVISING OPERATORS THAT LEAKS COULD OCCUR IN THE FWD PRESSURE BULKHEAD AREA BECAUSE OF METAL FATIGUE. DOUGLAS RECOMMENDED THAT SPECIFIC CORRECTIVE ACTION BE TAKEN WHICH INVOLVED INSPECTING THE AREA AT 1,500 HOUR INTERVALS OR MAKING PERMANENT STRUCTURAL AIRFRAME MODIFICATIONS. CONTRARY TO THE MAJORITY OF ACFT OPERATORS, UNITED CHOSE NOT TO STRUCTURALLY MODIFY THIS ACFT. RATHER, IT CHOSE TO PERFORM RECURRING VISUAL INSPECTIONS FOR LEAKS IN THE SUSPECT AREA. THE ACFT'S PRESSURE BULKHEAD RUPTURED 1,367 HRS AFTER IT LAST INSPECTION.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
RUPTURE OF A FORWARD PRESSURE BULKHEAD BECAUSE OF CYCLICALLY INDUCED METAL FATIGUE. FACTORS WHICH CONTRIBUTED TO THE INCIDENT WERE: THE OPERATOR'S DECISION NOT TO STRUCTURALLY MODIFY ITS AIRPLANE IN ACCORDANCE WITH THE MANUFACTURER'S BUT RATHER TO RELY ON THE MANUFACTURER'S ALTERNATIVE RECOMMENDATION OF PERFORMING REPETITIVE VISUAL INSPECTION IN THE SUSPECT AREA: AND THE OPERATOR'S FAILURE TO UTILIZE AN INSPECTION PROGRAM ADEQUATE TO VISUALLY DETECT CRACK DEVELOPMENT IN A PREVIOUSLY IDENTIFIED SUSPECT AREA.
NTSB Identification: SEA91IA081 .
The docket is stored on NTSB microfiche number 44378.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Incident occurred Tuesday, April 09, 1991 in SEATTLE, WA
Probable Cause Approval Date: 5/5/1993
Aircraft: BOEING 737-222, registration: N9003U
Injuries: 2 Minor, 31 Uninjured.
DURING THE INITIAL CLIMB, THE FLIGHT CREW HEARD A LOUD BANG FOLLOWED BY AIRFRAME VIBRATIONS. THE CREW WAS NOTIFIED BY THE CONTROL TOWER THAT SMOKE AND FLAME WERE EMITTING FROM THE LEFT ENGINE. THE FLIGHT CREW DECLARED AN EMERGENCY AND WAS CLEARED TO LAND. THE PILOT DISCHARGED A BANK OF FIRE EXTINGUISHING AGENT AND SHUT THE ENGINE DOWN. THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. DURING THE FOLLOW-UP INVESTIGATION, IT WAS FOUND THAT A TURBINE BLADE FAILED IN FATIGUE. THE FLIGHT CREW HAD RECEIVED AN INDICTION THAT THE FIRE EXTINGUISHING AGENT HAD DISCHARGED, HOWEVER, IT WAS LATER FOUND THAT IT DIDN'T DUE TO THE INSTALLATION OF AN INCORRECT DISCHARGE OUTLET. THE REAR EMERGENCY SLIDE ON THE RIGHT SIDE WAS SLOW IN INFLATING AND WAS NOT USABLE FOR THE EVACUATION. THE SLIDE WAS INSTALLED ON A TEST STAND AND FOUND TO OPERATE WITHIN NORMAL OPERATING PARAMETERS.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
TURBINE BLADE FAILURE FROM FATIGUE. FACTORS TO THE INCIDENT WERE INOPERATIVE ENGINE FIRE EXTINGUISHER, INADEQUATE SERVICE OF AIRCRAFT AND DELAYED DEPLOYMENT OF EMERGENCY SLIDE.
NTSB Identification: LAX90IA293 .
The docket is stored on NTSB microfiche number 45477.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Incident occurred Tuesday, August 21, 1990 in LOS ANGELES, CA
Probable Cause Approval Date: 12/30/1992
Aircraft: BOEING 737-322, registration: N305UA
Injuries: Unavailable
THE FLIGHT OF UAL FLIGHT 1257 WAS UNEVENTFUL UNTIL THE CREW EXTENDED THE LANDING GEAR FOR LANDING AT THE DESTINATION AND RECEIVED AN UNSAFE RIGHT MAIN LANDING GEAR INDICATION. THE CREW WAS UNABLE TO EXTEND THE GEAR AND PRECEDED TO AN AIRPORT WITH A LONGER RUNWAY FOR A GEAR UP LANDING. THE LANDING WAS ACCOMPLISHED WITHOUT INJURIES. THE RIGHT POWERPLANT NACELLE RECEIVED INCIDENTAL DAMAGE DURING THE LANDING TOUCHDOWN. WHEN THE RIGHT LANDING GEAR WAS OPENED A 3 CELL FLASHLIGHT WAS FOUND SANDWICHED BETWEEN THE CARGO FLOORING AND THE LANDING GEAR RETRACT/EXTEND LINKAGE.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
IMPROPER MAINTENANCE SERVICE BY A COMPANY EMPLOYEE WHO ALLOWED A FOREIGN OBJECT (FLASHLIGHT) TO REMAIN IN THE LANDING GEAR EXTEND/RETRACT LINKAGE DURING A NIGHT SERVICING BEFORE THE FLIGHT.
NTSB Identification: CHI88IA011 .
The docket is stored on NTSB microfiche number 37982.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Incident occurred Wednesday, October 28, 1987 in CHICAGO, IL
Probable Cause Approval Date: 7/10/1989
Aircraft: MCDONNELL DOUGLAS DC-10-10, registration: N1813U
Injuries: 228 Uninjured.
A WING PANEL SEPARATED FROM THE AIRPLANE WHILE IN CRUISE FLIGHT. CREW DECLARED AN EMERGENCY AND LANDED WITHOUT FURTHER INCIDENT. EXAMINATION REVEALED THAT MAINTENANCE PERSONNEL DID NOT FASTEN 4 OF THE 5 ROD END ASSEMBILIES USED TO SECURE THE PANEL TO THE TOP OF THE WING.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
WING,SKIN..NOT SECURED
MAINTENANCE,INSTALLATION..IMPROPER..OTHER MAINTENANCE PERSONNEL
MAINTENANCE,INSPECTION..POOR..OTHER MAINTENANCE PERSONNEL
NTSB Identification: LAX87LA243B.
The docket is stored on NTSB microfiche number 40095.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES (D.B.A. operation of UNITED AIRLINES )
Accident occurred Monday, June 22, 1987 in LOS ANGELES, CA
Probable Cause Approval Date: 11/28/1989
Aircraft: BOEING 747SP, registration: N141UA
Injuries: 83 Uninjured.
A BOEING 747SP COLLIDED WITH THE TAIL OF A BOEING 737. THE 737 WAS LINED UP ON A PARALLEL TAXIWAY AWAITING DEPARTURE. THE 747 WAS TAXIING FROM A TERMINAL GATE TO MAINTENANCE. THE 747 WAS BEING OPERATED BY TWO MECHANICS. ONE OF THE MECHANICS WAS NOT QUALIFIED TO TAXI THE 747. NO. 4 ENG HUNG START AND WAS NOT RUNNING DURING TAXI. THE NO. 4 ENG HYD SYS WAS SWITCHED OFF. THE NO. 4 HYD SYS IS THE PRIMARY POWER FOR THE ACFT BRAKE SYS. THE 747'S INERTIAL NAV SYS (INS) IS REQUIRED TO OPERATE WHILE TAXIING FOR SPEED REFERENCE. THE INS WAS ALSO SWITCHED OFF. THE 747 SPEED BECAME EXCESSIVE ON PARALLEL TAXIWAY. WHEN MECH ATTEMPTED TO STOP THERE WAS NO BRAKE POWER. HE DID NOT ACTIVATE THE EMER BRAKE SYS POWERED BY NO. 2 ENG HYD SYS. THE MECH SWERVED THE 747 TO THE LEFT. THE 747 R WING COLLIDED WITH TAIL OF 737. THE AIRLINE MAINT SUPERVISOR OF 747'S WAS AWARE OF MECH NON-QUAL AND OF THE NO. 4 ENG NOT OPERATING. DECISION WAS MADE TO LET THE ACFT TAXI CONTRARY TO PROCEDURES.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
FAILURE OF THE QUALIFIED MECHANIC TO INSURE THE OPERATION OF THE AIRCRAFT BRAKES PRIOR TO TAXIING AND HIS FAILURE TO UTILIZE THE EMERGENCY BRAKE SYSTEM TO PREVENT THE COLLISION. CONTRIBUTING TO THIS ACCIDENT WAS THE DECISION OF AIRLINE MAINTENCE SUPERVISORS TO ALLOW A NON QUALIFIED MECHANIC TO PERFORM RIGHT SEAT/FLIGHT ENGINEER PANEL DUTIES. ALSO CONTRIBUTING WAS THE QUALIFIED MECHANICS FAILURE TO USE THE AIRCRAFT'S INERTIAL NAVIGATION SYSTEM FOR CROSS REFERENCE TO TAXI SPEED.
NTSB Identification: CHI86FA119 .
The docket is stored on NTSB microfiche number 34465.
Scheduled 14 CFR Part 121: Air Carrier operation of UNITED AIRLINES
Accident occurred Tuesday, April 08, 1986 in CHICAGO, IL
Probable Cause Approval Date: 1/25/1988
Aircraft: BOEING 737-222, registration: N9054U
Injuries: 1 Minor, 113 Uninjured.
THE LEFT MAIN LANDING GEAR COLLAPSED MOMENTS AFTER TOUCHDOWN. WINDS AS REPORTED BY THE TWR WERE FROM 350 DEGS AT 19 KTS GUSTING TO 29 KTS. THE CAPTAIN AND COPILOT REPORTED THE TOUCHDOWN WAS NORMAL. THE 3 FLIGHT ATTENDANTS SAID THE AIRCRAFT LANDED HARD AND STARTED SHAKING VERY BADLY. THE FLIGHT ATTENDANTS ALSO REPORTED THAT THE PREVIOUS 2 LANDINGS HAD BROUGHT A GREAT DEAL OF VIBRATING/SHAKING TO THE AIRCRAFT. THE LEFT MAIN LANDING GEAR TEE BOLT WAS FOUND SEPARATED. METALLURGICAL EXAMINATION OF THE TEE BOLT SHOWED THE FRACTURE EMANATED FROM A SHALLOW PREEXISTING CRACK IN THE DRAG BRACE BEARING SURFACE RADIUS THAT THE METALLURGIST FOUND TO BE SHARPER THAN DESIRED. THE COLLAPSE OF THE LANDING GEAR IS CONSIDERED RELATED TO THE FRACTURED TEE BOLT. THE SAFETY BOARD IS UNABLE TO DETERMINE WHETHER OTHER EVENTS, CIRCUMSTANCES OR CONDITIONS WERE PRESENT THAT CONTRIBUTED TO THE TEE BOLT FAILURE IN THIS INSTANCE. THE OPERATOR HAS AMENDED THEIR REPAIR SPECIFICATIONS FOR THE TEE BOLTS.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
LANDING GEAR,MAIN GEAR..FATIGUE
PROCEDURES/DIRECTIVES..NOT FOLLOWED..COMPANY MAINTENANCE PERSONNEL
NTSB Identification: DCA85IA019 .
The docket is stored on NTSB microfiche number 27825.
Nonscheduled 14 CFR Part 121: Air Carrier operation of UNITED AIR CARRIERS (D.B.A. NATIONAL AIRLINES, INC. )
Incident occurred Thursday, April 25, 1985 in DETROIT, MI
Aircraft: BOEING 747-123, registration: N9663
Injuries: 42 Minor, 439 Uninjured.
THE FLT CREWMEMBERS OF THE JUMBO JET WERE PREPARING TO START THE ENGS WHEN FLT ATTENDANTS (F/A'S) IN THE FORWARD CABIN DETECTED A FAINT ODOR PRIOR TO CLOSING DOOR 1L. THE SOURCE COULD NOT BE DETERMINED, SO THE DOOR WAS CLOSED IN PREPARATION FOR A PUSHBACK. SHORTLY THEREAFTER, SMOKE WAS DISCOVERED IN THE VICINITY OF THE OVERHEAD BIN AT ROW 16. THE CAPTAIN WAS NOTIFIED & HE ORDERED THAT 'OCCUPANTS EVACUATE, IF THERE IS A FIRE ONBOARD.' THE JETWAY WAS BROUGHT BACK TO DOOR 1L. THE SMOKE DISSIPATED; THUS, THE F/A'S AT DOORS 1R, 2L & 2R DID NOT OPEN THEIR DOORS. HOWEVER, THE F/A'S AT THE OTHER 6 DOORS WERE UNAWARE OF THE SITUATION & CONTINUED THE EVACUATION. THE RAMPS AT DOORS 3L & 3R DID NOT INFLATE & DOOR 5R JAMMED HALFWAY OPEN. THE RAMP PACKS FOR 3R & 3L WERE IMPROPERLY MOUNTED. THE 5R PACK BOARD WAS MADE FOR A LEFT HAND DOOR & THE LANYARD WAS NOT CONNECTED TO THE BOTTOM PANEL PULLEY. AN EXAM REVEALED A BALLAST FOR AN OVERHEAD FLOURESCENT LIGHT, PN 69-33C, HAD OVERHEATED & MELTED THE PLASTIC CASE.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
PASSENGER COMPARTMENT LIGHT(S)..OVERTEMPERATURE
Contributing Factors
MAINTENANCE,SERVICE BULLETIN/LETTER..NOT FOLLOWED..COMPANY/OPERATOR MANAGEMENT
MISC EQPT/FURNISHINGS,SLIDES..INOPERATIVE
MAINTENANCE,INSTALLATION..IMPROPER..COMPANY MAINTENANCE PERSONNEL
DOOR,EMERGENCY EXIT..IMPROPER
MAINTENANCE,INSTALLATION..IMPROPER..COMPANY MAINTENANCE PERSONNEL
DOOR,EMERGENCY EXIT..JAMMED
NTSB Identification: CHI84IA264 .
The docket is stored on NTSB microfiche number 26895.
Scheduled 14 CFR Part 121: Air Carrier UNITED AIRLINES
Incident occurred Tuesday, June 26, 1984 in CHICAGO, IL
Probable Cause Approval Date: 8/30/1994
Aircraft: McDonnell Douglas DC-8-54, registration: N8048U
Injuries: 3 Uninjured.
DURING THE LANDING ROLL, THE LEFT MAIN GEAR SWIVEL LINK PIN FAILED ALLOWING THE REAR SET OF TIRES TO BECOME DETACHED FROM THE MAIN STRUT AND DRAG ALONG THE RWY. THE LEFT MAIN GEAR BOGIE WAS LAST OVERHAULED IN 1981. AT THE TIME OF FAILURE, IT HAD 4459 HOURS SINCE OVERHAUL. METALLURGICAL STUDY OF THE SWIVEL PIN REVEALED, 1) INTERGRANULAR CRACKING THRU 40% OF PIN CROSS-SECTION, 2) EVIDENCE OF STRESS CORROSION FROM OVERTORQUING THE NUT ON THREADED END OF PIN, 3) TRACES OF COPPER, SOMETIMES USED BEFORE CHROMIUM PLATING DURING OVERHAUL, FOUND IN CRACK, 4) NO OVERLOAD EVIDENCE IN PREEXISTANT CRACK, AND 5) INDICATIONS THAT FINAL FRACTURE WAS DUE TO OVERLOAD.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
MAINTENANCE..IMPROPER..PILOT IN COMMAND
LANDING GEAR,MAIN GEAR ATTACHMENT..OVERTORQUE
LANDING GEAR,MAIN GEAR ATTACHMENT..STRESS CORROSION
LANDING GEAR,MAIN GEAR ATTACHMENT..FAILURE,TOTAL
NTSB Identification: LAX84IA351 .
The docket is stored on NTSB microfiche number 27126.
Scheduled 14 CFR Part 121: Air Carrier UNITED AIRLINES
Incident occurred Sunday, June 10, 1984 in LOS ANGELES, CA
Probable Cause Approval Date: 8/30/1994
Aircraft: MCDONNELL DOUGLAS DC-10-10, registration: N1806U
Injuries: 212 Uninjured.
THE PILOTS WERE UNABLE TO RETRACT THE RIGHT WING SPOILERS AFTER TAKEOFF, SO THEY RETURNED TO THE DEPARTURE AIRPORT FOR AN UNEVENTFUL LANDING. AN INSPECTION REVEALED RUST & DEBRIS IN THE AREA OF THE BELLCRANK, WHICH PREVENTED THE #1, #4 & #5 RGT HAND SPOILERS FROM RETRACTING. THE SPOILERS REMAINED EXTENDED 4 TO 5 INCHES.
The National Transportation Safety Board determines the probable cause(s) of this incident as follows:
FLT CONTROL SYST,WING SPOILER SYSTEM..CORRODED
FLT CONTROL SYST,WING SPOILER SYSTEM..MOVEMENT RESTRICTED
