Dehavilland TIGER MOTH DH 82A accident near Fontana, California, June 24, 2012
On June 24, 2012 at about 2:55 am local time, a Dehavilland TIGER MOTH DH 82A, registered N523R, was substantially damaged in an accident during enroute (cruise) near Fontana, California (Flabob airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made November 2, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 24, 2012 · about 2:55 am local time · cases in 2012
- Place
- Fontana, California · Flabob · cases near this airport · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Dehavilland TIGER MOTH DH 82A · all TIGER MOTH DH 82As on the register
- Registration
- N523R · registry record · serial 82960
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Loss of engine power (partial) during enroute (cruise) defining event
- Off-field or emergency landing during emergency descent
- Nose over/nose down during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Fatigue/wear/corrosion other cases naming the engine
- factor Personnel issues › Task performance › Maintenance › Modification/alteration › Maintenance personnel
Pilot
- Certificate: airline transport pilot, flight instructor, flight engineer
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 13,800 hours in all; 400 in this make and model; 100 in the last 90 days; 30 in the last 30 days; 10,800 as pilot in command; 2,000 on instruments
- Last flight review: April 12, 2012
- Medical certificate: Class 1 (with waivers/limitations)
- Seat: rear
- Injury: no injuries
The aircraft
- Airframe total time: 3,472 hours
- Last inspection: annual inspection, November 1, 2011; 17 hours since
- Maximum gross weight: 1,800 lb
- Seats: 2
- Landing gear: fixed
- Engine: Dehavilland GIPSY MAJOR (piston); 0 hours total
The flight
- Departed from: KRIR Flabob CA at 2:50 am
- Destination: KCCB Upland CA
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 280° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 73°F (23°C), dew point 54°F (12°C)
- Altimeter: 29.81 inHg
- Observation at 2:53 am from KRAL, 7 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
10 documents, released by the NTSB on October 24, 2012. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Photo 1 – Fuselage Damage | PDF, 1 page | View Download |
| 3 | Photo 2 – Cylinder 4 Rocker Area | PDF, 1 page | View Download |
| 4 | Photo 3 – Cylinder 4 Exhaust Valve Stem | PDF, 1 page | View Download |
| 5 | Photo 4 - Cylinder 4 Forward Clamping Bolt | PDF, 1 page | View Download |
| 6 | Photo 5 - Cylinder 4 Forward Clamping Nut | PDF, 1 page | View Download |
| 7 | Photo 6 - Cylinder 4 Forward Clamping Bolt Separation Surface | PDF, 1 page | View Download |
| 8 | Photo 7 – Components for Modification News Sheet 1448 | PDF, 1 page | View Download |
| 9 | Maintenance Manual Excerpts | PDF, 2 pages | View Download |
| 10 | Modification News Sheet 1448 | PDF, 8 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
Connections how this case links to the rest of the register
- N523R on the register today · the tail number may have moved to another aircraft since
- Dehavilland TIGER MOTH DH 82A 52 registered today · the model family and its accident history
- Dehavilland 861 aircraft on the register
- Engine: Dehavilland GIPSY MAJOR · as the NTSB recorded it
- Flabob Airport · nearest airport
- Flabob Airport · departed from
- Cable Airport · bound for
- Accidents and incidents in California 9,080 since 1982 · 1,098 in the last ten years
- California 27,686 aircraft registered
The whole map of how records connect · these connections as data: /graph/accident/WPR12LA275.json.
The bigger picture in Aviation Analytics: accidents over time since 1982, by model, by phase of flight and conditions, by place and on the map.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text does not name anyone involved, its policy at this time. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.