Individually Owned: 150,657
Corporate Owned: 137,281
Half Moon Bay Airport
Aircraft Accident/Incident Report
Half Moon Bay, California 94019
Monday, March 22, 2010 14:30 PDT
NTSB Narrative Summary Released at Completion of Accident
Prior to landing the pilot observed 3 green lights indicating that the landing gear was down and locked. During the landing roll the left main landing gear collapsed, which resulted in substantial damage to the left wing and aileron. A Federal Aviation Administration inspector reported that a postaccident examination of the left main landing gear's pneumatic actuator revealed that the actuator's down-lock ball track was contaminated with dirt and that the steel down-lock balls were corroded. The combination of dirt in the actuator's down-lock track, the corroded down-lock balls, and the low down-lock pressure likely caused the gear to collapse.
NTSB Probable Cause Narrative
The failure of left main landing gear actuator to lock in the down position due to low down-lock pressure as a result of a contaminated down-lock track and corroded down-lock balls.
Event Information
| Type of Event | Accident |
| Event Date | 3/22/2010 |
| Event Day of the Week | Monday |
| Time of Event | 1430 |
| Event Time Zone | Pacific Daylight Time |
| Event City | Half Moon Bay |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 94019 |
| Event Date Year | 2010 |
| Event Date Month | 3 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 373049N |
| Event Location Longitude | 1223004W |
| Event Location Airport | Half Moon Bay |
| Event Location Nearest Airport ID | HAF |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 67 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1435 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | HAF |
| Elevation of weather observation facility | 66 |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 6 |
| Air Temperature at event time (in degrees celsius) | 14 |
| Dew Point at event time (in degress fahrenheit) | 9 |
| Wind Direction (degrees magnetic) | 330 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 15 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Gusting |
| Wind Gust (knots) | 21 |
| Altimeter Setting at event time (in. Hg) | 30.07 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 1 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 27012 |
| NTSB Notification Source | Regional Operations Center |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Jun 7 2010 7:56PM |
| User who most recently changed record | stam |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N153U |
| NTSB Number | WPR10LA173 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Williams Yakovlev |
| Aircraft Model | YAK 3UPW |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 005 |
| Certified Max Gross Weight | 6143 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 2 |
| Number of Engines | 1 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Mar 1 2010 12:00AM |
| Airframe hours since last inspection | 21 |
| Airframe Hours | 21 |
| ELT Installed | Yes |
| ELT Activated | Yes |
| ELT Aided Location of Event Site | No |
| ELT Type | Unknown |
| Aircraft Owner Name | Yak Aviation LLC |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Half Moon Bay |
| Aircraft Owner State | CA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 94019 |
| Operator is an individual? | No |
| Operator Name | James A Williams |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | Half Moon Bay |
| Operator State | CA |
| Operator Country | USA |
| Operator Zip code | 94019 |
| Operator Code | -- |
| Owner has at least one certificate | None |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | -- |
| Indicates Domestic or International Flight | -- |
| Operator carrying Pax/Cargo/Mail | -- |
| Type of Flying (Per_Bus / Primary) | Personal |
| Second Pilot on Board | No |
| Departure Point Same as Event | Yes |
| Departure Airport Code | HAF |
| Departure City | Half Moon Bay |
| Departure State | CA |
| Departure Country | USA |
| Departure Time | 1410 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | dest & departure same, accident can occur anywhere |
| Destination Airport Code | HAF |
| Destination City | Half Moon Bay |
| Destination State | CA |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jun 7 2010 7:57PM |
| User who most recently changed record | stam |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | 30 |
| Runway Length | 5000 |
| Runway Width | 150 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |