NYC99LA139 · Aero Commander 500S
Aero Commander 500S · Accident: airframe, component or system failure on approach
From Westchester County Airport (HPN) to Bradley International Airport (BDL)
Event
- NTSB case
- NYC99LA139
- 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
Aero Commander 500S
- Aircraft type
- Aero Commander 500
- 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
- N33PG
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Westchester County Airport (HPN), White Plains, NYTo Bradley International Airport (BDL)
- 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
- 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
- Substantial
Cause areas
- Hydraulic system › Contamination
Approximate · Estimated position: the centre of Windsor Locks, CT, the place the record names. Not the accident site.
NTSB narrative
The pilot in command was flying the airplane with a safety pilot onboard. After multiple approaches, when the landing gear was extended, only the nose landing gear extended. Unable to extend the main landing gear, the pilot in command requested that the second pilot perform the gear up landing, because of his greater experience. The propellers were feathered prior to touchdown, and the airplane touched down hard, crushing the lower aft fuselage. Examination of the hydraulic system revealed contamination in the system. According to the mechanic who worked on the airplane, '...the contamination caused the main gear uplock cylinder not to release and allow the gear to extend....' The airplane is not equipped with an alternate gear extension system, therefore, if the hydraulic uplock valve cannot be released, the main gear cannot be extended.
Probable cause
Hydraulic system contamination which prevented normal landing gear extension. A factor was the misjudged landing flare by the flying pilot.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record NYC99LA139
- Event ID
- 20001212X19092
- Case number
- NYC99LA139
- 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: 9880bcc2684b91ea7e88b1b71854a5a212b35aedf05f5317f263603f3e19e704; retrieved 2026-09-22T14:52:46.629Z.