NYC99IA079 · Cessna 550
Cessna 550 · Incident: gear collapsed while taxiing
From Allegheny County Airport (AGC) to UNV
Event
- NTSB case
- NYC99IA079
- 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
- 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
Cessna 550
- Aircraft type
- Cessna 550
- 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
- N37MH
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Allegheny County Airport (AGC), Pittsburgh, PATo UNV
- 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
- Taxi · from runway
- 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
- Gear collapsed
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Minor
Cause areas
- Manufacturer › Maintenance, improper
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
When the airplane's left main gear actuator was removed for overhaul, a temporary replacement, provided by the airplane manufacturer, was installed. While taxing after landing, the airplane's left main landing gear collapsed. Disassembly of the actuator revealed the lock ring was installed upside-down. A radiograph view of taken of the lock piston and the ball bearing which operated the lock switch revealed the ball bearing was resting only 1/2 up the ramp on the lock piston; however, the downlock switch was found to indicate locked. Review of the actuator's maintenance records revealed it was repaired by the Cessna Wichita Citation Service Center, Wichita, Kansas, on February 7, 1999. During the repair, the actuator was dissembled and reassembled.
Probable cause
Improper assembly of the left main landing gear (LMLG) actuator by the airplane manufacturer, which resulted in an incorrect 'locked' indication on the LMLG switch, and the subsequent collapse of the LMLG during taxi.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record NYC99IA079
- Event ID
- 20001205X00379
- Case number
- NYC99IA079
- 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: f56bc255cc4375cf899400c9b67761ad83a10e608ea2f30dc17a7ba56241de0b; retrieved 2026-09-22T15:38:09.976Z.