North American NAVION accident near Alamogordo, New Mexico, June 24, 2016
On June 24, 2016 at about 4:15 pm local time, a 1946 North American NAVION, registered N91137, was substantially damaged in an accident during landing near Alamogordo, New Mexico. 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
The failure of the No. 5 exhaust valve key spring, which resulted in a total loss of engine power.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 24, 2016 · about 4:15 pm local time
- Place
- Alamogordo, New Mexico · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- North American NAVION A, built 1946 · all NAVIONs on the register
- Registration
- N91137 · no longer on the register · serial NAV-4-31
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The commercial pilot stated that, while in cruise flight, the engine began to run rough and that he noted that the Nos. 1 and 5 cylinders were indicating significantly cooler temperatures than the other cylinders. About 12 minutes later, the pilot noticed an "acrid metallic smell" in the cabin. The pilot turned the airplane toward the closest airport as the engine continued to run rough and produce a "metallic clanking" sound. Unable to reach the airport, the pilot made a forced landing in a field about 100 yards short of a road. The airplane continued into a drainage culvert and came to rest on the road. A postaccident examination of the engine revealed that the engine crankcase was cracked at the base of the No. 5 cylinder and the cylinder's rocker box cover exhibited multiple holes. The oil sump contained a large amount of metal debris and damaged components from the No. 5 cylinder. The No. 5 cylinder exhaust valve spring key was worn and damaged. The exhaust valve guide was fragmented and the valve guide bore was worn beyond the specified size, which indicated the valve guide was moving inside the guide bore. The No. 5 piston and cylinder damage were a result of the valve being released into the cylinder during engine operation. It is likely that the valve spring key failed and allowed the valve to release into the cylinder.
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
- Loss of engine power (total) during landing defining event
- Off-field or emergency landing during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip eng cyl section › Failure
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane
- Flight time: 1,193 hours in all; 1,061 in this make and model; 42 in the last 90 days; 17 in the last 30 days; 1,061 as pilot in command
- Last flight review: March 4, 2016
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 3,600 hours
- Last inspection: annual inspection, March 23, 2016
- Seats: 4
- Landing gear: retractable
- Engine: Continental Motors IO-520-B (piston); 1,099 hours total
The flight
- Departed from: SRR Ruidoso NM at 3:38 pm
- Destination: SRR Ruidoso NM
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 230° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 86°F (30°C), dew point 48°F (9°C)
- Altimeter: 30.12 inHg
- Observation at 3:55 pm from KALM, 4 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
9 documents, released by the NTSB on April 20, 2017. 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 | Pilot's Email Statement | PDF, 2 pages | View Download |
| 3 | Maintenance Records | PDF, 3 pages | View Download |
| 4 | Continental Motors Examination Report | PDF, 28 pages | View Download |
| 5 | Continental Motors Cylinder Report | PDF, 4 pages | View Download |
| 6 | Engine Manual Excerpts | PDF, 3 pages | View Download |
| 7 | Figures and Photos | PDF, 6 pages | View Download |
| 8 | Statement of Party Representatives to NTSB Investigation | PDF, 1 page | View Download |
| 9 | Release of Aircraft Wreckage, NTSB Form 6120.15 | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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 never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.