LAX98LA053 · McDonnell Douglas 369HS
Micronesian Aviation McDonnell Douglas 369HS · Accident: partial loss of engine power (mechanical failure) on approach
Narrative check · The NTSB narrative appears to contradict this record's location. Values are shown as recorded, not corrected; compare with the narrative.
Event
- NTSB case
- LAX98LA053
- 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
- Accident
- 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
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
McDonnell Douglas 369HS
- Aircraft type
- McDonnell Douglas 369
- Category
- Helicopter
- 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
- N9068F
- Operator
- Micronesian Aviation
- Onboard fatalities
- Unknown
- Route
- From not recordedTo not recorded
- 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 91: General Aviation
- 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
- Approach · VFR pattern final
- 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
- Partial loss of engine power (mechanical failure)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Fuel system, fuel control › Flow restricted
- Other maintenance personnel › Maintenance, overhaul, improper
- Other maintenance personnel › Maintenance, service bulletin/letter, not complied with
Approximate · Estimated position: the centre of Saipan, the place the record names. Not the accident site.
NTSB narrative
The pilot reported that he was making a standard approach to the helicopter pad which was located on a bluff overlooking a golf course. About 100 yards from the pad and 150 feet agl, he noticed a twitch in the nose of the aircraft and heard the rpm decreasing and the engine spooling down. He entered an autorotation and turned the helicopter to the right to avoid upsloping terrain. The aircraft touched down hard and the landing gear collapsed and the tail rotor struck the ground. The pilot stated that after coming to a stop, the engine was still idling so he closed the fuel shutoff valve and throttle and turned off all electrical power. The engine took about 20 to 30 seconds to spool down. The fuel control components were then tested at the Allied Signal Materials Technology Center in South Bend, Indiana, under the auspices of the FAA. Operational bench tests performed on the fuel control and governor indicated that the fuel control would meter minimum fuel flow throughout the various test points and that the acceleration bellows assembly was the probable source for the uncommanded minimum fuel flow condition. A leak was found in the bellows which stemmed from a corrosion pit that penetrated through the outer ply of a convolution tube at the edge of a braze fillet. The pit caused evacuation and malfunction of the bellows. Allied Signal and Allison Engines issued service bulletins on November 18, 1993, regarding the replacement of the fuel control bellows. The Allison Commercial Engine Bulletin CEB-A-282 directed that the beryllium copper bellows be replaced by a stainless steel welded Pc Inconel Bellows the next time the affected fuel control was at a repair/overhaul facility and the bellows area was disassembled for any reason, but in no case later than the next fuel control unit overhaul. The aircraft maintenance records revealed that on April 22, 1997, an overhaul of the fuel control assembly was performed. On a form indicating compliance with applicable service bulletins and directives, 'NA' was written by the maintenance facility in the space next to the listing for the Allison CEB-282. The records revealed that the fuel control with the beryllium copper Pc bellows was reinstalled in the helicopter on October 1, 1997, at engine time 2,247.1 hours, 39 hours prior to the accident.
Probable cause
The failure of the maintenance facility to comply with the service bulletins, which resulted in the development of a corrosion pit, subsequent leakage and failure of the acceleration bellows of the fuel control.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX98LA053
- Event ID
- 20001208X09331
- Case number
- LAX98LA053
- 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: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 12b8aa417209ffafb8517782377d88b3870f45cfc6bd84d8daec3cb179af9600; retrieved 2026-09-21T21:01:48.815Z.