Individually Owned: 150,657
Corporate Owned: 137,281
Flabob Airport
Aircraft Accident/Incident Report
Fontana, California 92335
Saturday, June 23, 2012 19:55 PDT
NTSB Narrative Summary Released at Completion of Accident
During cruise flight, the engine lost partial power. The pilot performed a forced landing into a field, and the airplane nosed over. Postaccident examination of the engine revealed that a rocker bracket assembly clamping bolt had failed in fatigue, causing the assembly to partially detach from the cylinder head. The detachment prevented the exhaust valve from actuating. Peening damage sustained to the bolt revealed that it most likely failed during a prior flight, at an undetermined time before the ultimate displacement of the bracket assembly.
No airworthiness directives existed for the antique engine, which was overhauled 46 years prior to the accident. However, a “modification news sheet” was issued by the manufacturer 16 years before the overhaul, which detailed a design change intended to preclude the failure of the clamping bolts. The modification was not performed on the failed cylinder; however, the three other cylinders exhibited an undocumented modification to their rocker valve assemblies, which appeared to perform the same function.
NTSB Probable Cause Narrative
Partial loss of engine power during cruise flight due to a failed engine cylinder rocker assembly clamping bolt. Contributing to the accident was the failure of unknown maintenance personnel to perform a modification to the assembly that would have prevented the failure.
Event Information
| Type of Event | Accident |
| Event Date | 6/23/2012 |
| Event Day of the Week | Saturday |
| Time of Event | 1955 |
| Event Time Zone | Pacific Daylight Time |
| Event City | Fontana |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 92335 |
| Event Date Year | 2012 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 340257n |
| Event Location Longitude | 1172755w |
| Event Location Airport | Flabob |
| Event Location Nearest Airport ID | RIR |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 5 |
| Degrees magnetic from airport | -- |
| Airport Elevation | 764 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1953 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | 180 |
| Weather Observation Facility ID | KRAL |
| Elevation of weather observation facility | 819 |
| Distance of event from weather observation facility (units?) | 7 |
| 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) | 10 |
| Air Temperature at event time (in degrees celsius) | 23 |
| Dew Point at event time (in degress fahrenheit) | 12 |
| Wind Direction (degrees magnetic) | 280 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 8 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 29.82 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | METAR KRAL 240253Z 28008KT 10SM CLR 23/12 A2982 RM |
| 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 | 2 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 30654 |
| NTSB Notification Source | FAA ROC |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Oct 24 2012 6:23PM |
| User who most recently changed record | coos |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N523R |
| NTSB Number | WPR12LA275 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | No |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | DEHAVILLAND |
| Aircraft Model | TIGER MOTH DH 82A |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 82960 |
| Certified Max Gross Weight | 1800 |
| 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 | Fixed |
| Aircraft, Type of Last Inspection | Annual |
| Date of Last Inspection | Nov 1 2011 12:00AM |
| Airframe hours since last inspection | 17 |
| Airframe Hours | 3472 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | NICHOLAS BAKER |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | UPLAND |
| Aircraft Owner State | CA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 91784-8332 |
| Operator is an individual? | Yes |
| Operator Name | NICHOLAS BAKER |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | UPLAND |
| Operator State | CA |
| Operator Country | USA |
| Operator Zip code | 91784-8332 |
| 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 | No |
| Departure Airport Code | KRIR |
| Departure City | Flabob |
| Departure State | CA |
| Departure Country | USA |
| Departure Time | 1950 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | KCCB |
| Destination City | Upland |
| Destination State | CA |
| Destination Country | USA |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Oct 24 2012 6:14PM |
| User who most recently changed record | coos |
| Since inspection or accident | Last Inspection |
| Event Location Runway Number and Location | N/A |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |