Universal Moulded Pdts MONOCOACH N11872

Summary

On 17 August 2004 at about 16:30 local time, a Universal Moulded Pdts MONOCOACH registered N11872, operated by William C. Piper, was involved in an accident near Pullman, Washington, United States. 2 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 August 2004 at 16:30

Classification

Accident

Location

Pullman, Washington, United States

Nearest airport

Pullman-Moscow Reg. (PUW)

Coordinates

46.7486, -117.1356

Aircraft

Universal Moulded Pdts MONOCOACH

Registration

N11872

Category

Airplane

Engines

1

Operator

William C. Piper

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Porthill → Pullman

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA04LA162

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full 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.

Quoted verbatim from the NTSB record.