Amateur-built ACRO-SPECIAL accident near Earlham, Iowa, July 2, 1992
On July 2, 1992 at about 1:40 am local time, a amateur-built ACRO-SPECIAL, registered N79WA, was substantially damaged in an accident near Earlham, Iowa. It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured and 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A LOSS OF TOTAL ENGINE POWER WHEN A FAILED FLAPPER VALVE IN THE AIR BOX BLOCKED THE FLOW OF AIR THROUGH THE CARBURETOR THROAT.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 2, 1992 · about 1:40 am local time
- Place
- Earlham, Iowa · map
- Type
- Accident
- Injuries
- 1 person was seriously injured and 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built ACRO-SPECIAL ACRO-SPECI
- Registration
- N79WA · registry record · serial 3
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE HOMEBUILT ACCIDENT AIRPLANE LOST ENGINE POWER DURING INITIAL CLIMB FROM TAKEOFF. IT COLLIDED WITH TREES AND TERRAIN DURING A FORCED LANDING. THE PILOT DESCRIBED HOW HE HAD BEEN FLYING ABOUT 45 MINUTES AND HAD DONE TWO LANDINGS AND TAKEOFFS. DURING THE THIRD TAKEOFF THE AIRPLANE HAD CLIMBED ABOUT 75 TO 100 FEET WHEN THE ENGINE LOST POWER. EXAMINATION OF THE CARBURETOR AIR BOX REVEALED A FLAPPER VALVE IN THE AIR BOX HAD BROKEN. THE VALVE PLATE WAS FREE TO MOVE ABOUT IN THE SPACE BETWEEN THE SHAFT AND THE CARBURETOR AIR INTAKE. THE PLATE HAD BEEN SECURED TO THE SHAFT WITH TWO SPOT WELDS. THE SURFACE OF THE BROKEN WELDS APPEARED DULL EXCEPT FOR A SMALL PORTION ON ONE WELD WHERE THE BREAK APPEARED SHINY. THE CARBURETOR AIR BOX HAD BEEN PURCHASED FROM AN AIRCRAFT SALVAGE OPERATOR FOR INSTALLATION ON THE AIRPLANE.
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
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 357 hours in all; 5 in this make and model; 17 in the last 90 days; 9 in the last 30 days; 357 as pilot in command
- Medical certificate: Class 3 (expired)
- Seat: rear
The aircraft
- Airframe total time: 101 hours
- Last inspection: annual inspection, May 27, 1992; 10 hours since
- Maximum gross weight: 1,550 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-320-E2D (piston); 0 hours total
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: dusk
- Wind: from 180° at 7 knots
- Visibility: 7 statute miles
- Sky: broken clouds at 8,500 ft; not recorded
- Temperature: 84°F (29°C), dew point 66°F (19°C)
- Altimeter: 29.00 inHg
- Observation at 1:50 am from DSM, 25 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
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.