# Accident 20100420032199A: Yakovlev/Wi YAK 3UPW, Half Moon Bay, CA, April 20, 2010

- Type: FAA accident report (Accident/Incident Data System), as reported
- Date: April 20, 2010, 12:00 local time
- Place: Half Moon Bay, CA
- Airport: Half Moon Bay
- Damage: Substantial damage
- Phase of flight: Landing: Rollout
- Operating rules: General operating rules (Part 91)
- Location: 37.5134° N, 122.5012° W: Placed by OpenAirDocs at HALF MOON BAY (HAF), within about a mile (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=37.5134&lon=-122.5012&mi=10
- Aircraft: N153U (not matched to a registry record)
- Reported make and model: YAKOVLEV/WI YAK 3UPW
- Reported engine: P & W R-1830 SERIES
- People aboard: 1
- Fatal injuries: 0
- Other injuries: 0
- Pilot flight hours: 0 total, 0 in this make and model, 0 in the last 90 days
- FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/)
- Page: https://openairdocs.org/incident/20100420032199A

## Narrative

As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^.

THIS ACCIDENT WAS REOPENED WITH A NEW NTSB NUMBER.  SEE PREVIOUS REPORT A-WP-27-10-010.  NTSB PROVIDED FUNDING FOR LEFT MAIN LANDING GEAR TEAR DOWN ANALYSIS.  THE TEAR DOWN WAS ACCOMPLISHED ON 04/28/2010, FOLLOWING ARE THE RESULTS.  MECHANIC STATEMENT:I REMOVED THE LEFT MAIN LANDING GEAR ACTUATOR FROM ^PRIVACY DATA OMITTED^ YAK 3.USING SHOCK AIR, OPERATION OF THE ACTUATOR APPEARED TO BE NORMAL.THERE WERE NO INTERNAL OR EXTERNAL LEAKS.  AFTER DISASSEMBLING THEACTUATOR, I FOUND SOME DIRT CONTAMINATION IN THE DOWN LOCK BALL TRACK.  THE STEEL DOWN LOCK BALLS WERE ALSO CORRODED.  DOWN LINE AIR PRESSURENORMALLY FORCES THE BALLS INTO THE TRACK TO LOCK THE ACTUATOR IN THEDOWN POSITION.  THE DIRT CONTAMINATION COULD HAVE ENTERED THE SYSTEMTHROUGH THE ON-BOARD AIR PUMP.  IN SUMMARY I BELIEVE A COMBINATION OFDIRT IN THE DOWN LOCK TRACK, CORRODED DOWN LOCK BALLS, LOW DOWN LOCKPRESSURE AND PERHAPS A SLIGHT SIDE LOAD ON LANDING CAUSED THE GEAR TOCOLLAPSE.  FAA OBSERVATION:ACTUATOR WAS CONTAMINATED WITH WATER AND DIRT WAS NOTED IN THE BALL LOCK TRACK.  THE BALL LOCKS SHOWED EVIDENCE OF CORROSION AND ONE BALL HAD SEPARATED FROM IT KEEPER.

## NTSB investigation

None matched to this report by aircraft and date. Search the NTSB's own records: https://data.ntsb.gov/carol-main-public/basic-search

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.