Flight 37 · McDonnell Douglas MD-11
McDonnell Douglas MD-11 · Incident: airframe, component or system failure en route
From London Gatwick Airport (LGW) to CVG · Cincinnati, OH
Event
- NTSB case
- IAD97IA018
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Unknown
McDonnell Douglas MD-11
- Aircraft type
- McDonnell Douglas MD-11
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N814DE
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From London Gatwick Airport (LGW), GATWICKTo CVG · Cincinnati, OH
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Horizontal stabilizer › Jammed
- Production/design personnel › Improper use of procedure
- Production/design personnel › Maintenance, lubrication, not performed
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While en route the flight crew experienced a failure of the pitch trim control system. The crew was unable to change the pitch trim by the yoke mounted trim switches or the center console mounted horizontal stabilizer control handles. The crew stated that when the slats were extended on descent, they were unable to change stabilizer trim. Subsequent examination of the horizontal stabilizer pitch trim system found that there was no lubrication on the screw actuator assemblies and that the fuse pin had sheared in the output drive unit of the horizontal stabilizer drive gearbox. The sheared fuse pin locked the horizontal stabilizer in its last set position, as designed. A review of Assembly Orders at Douglas Aircraft (DAC) found that DAC production personnel and DAC Inspection personnel stamped the assembly orders indicating completion and acceptance of the lubrication. However, the investigation revealed that no lubrication had been applied to the screw actuator nuts.
Probable cause
Failure of the output drive unit shear pin due to lack of lubrication to the screw actuator assemblies. Contributing to the cause was the aircraft manufacturer's production and inspection personnel failing to lubricate the screw assemblies after initial installation and again after washing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record IAD97IA018
- Event ID
- 20001208X07045
- Case number
- IAD97IA018
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, damage. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 1996-11-08.
- API snapshot SHA-256: 740f63dfbeae898b648576fbebcdfe6b24a4dd0ad15b3fbcd91a66f40719d45f; retrieved 2026-09-18T17:45:43.688Z.