SEA04LA162 · Universal Moulded Pdts. Monocoach
Universal Moulded Pdts. Monocoach · Accident: airframe, component or system failure
From Eckhart International Airport (1S1) to Pullman-Moscow Regional Airport (PUW)
Event
- NTSB case
- SEA04LA162
- 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
- Unknown
- 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
Universal Moulded Pdts. Monocoach
- Aircraft type
- Universal Moulded Pdts MONOCOACH
- 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
- N11872
- Operator
- William C. Piper · private individual
- Onboard fatalities
- Unknown
- Route
- From Eckhart International Airport (1S1), Porthill, IDTo Pullman-Moscow Regional Airport (PUW), Pullman, WA
- 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
- Unknown
- 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
- Landing gear, main gear shock absorbing strut › Separation
- Miscellaneous, dowel/pin › Failure
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During a landing, just as the aircraft's two main wheels touched the surface of the runway, it suddenly jerked to the side and started to veer from the runway heading. The pilot therefore immediately added power and pulled the aircraft off the ground. He then climbed out to an altitude where he could visually inspect the gear legs and evaluate his situation. When he looked at the gear legs, he discovered that the left main gear strut oleo had come out of its housing, and the gear strut structure was hanging from the aircraft by two of its attach points. He therefore circled the area for awhile, waiting for emergency vehicles to get in place at the airport prior to his attempt to land on the remaining main gear. Once the equipment was in place, he landed on the grass alongside of the paved runway. The aircraft touched down on the right main gear, and the pilot kept the other gear leg elevated as long as possible. Eventually, as the aircraft slowed, the left gear strut dug into the terrain and collapsed. A post-accident inspection of the gear system determined that the landing gear shock strut retaining nut safety clip (snap ring) had failed, thus allowing the shock strut retaining nut to back off of its threads. Without this retaining nut in place, the oleo piston was free to drop out of its housing, leaving the landing gear only partially attached to the fuselage.
Probable cause
The failure of a landing gear oleo retaining nut safety clip (snap ring) at an unknown point in time, leading to the partial separation of the landing gear strut while in flight, and the full collapse of the strut during the subsequent landing. Factors include the grassy terrain that the pilot chose to execute the landing on.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record SEA04LA162
- Event ID
- 20040819X01259
- Case number
- SEA04LA162
- 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, coordinates. 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: b25c2ef21afce82e44bb9209e47e6e54a7cc765d333686f0e085e874a9eda43b; retrieved 2026-09-22T06:53:03.256Z.