Amateur-built ZENITH CH 750 accident near Allentown, Pennsylvania, August 14, 2015
On August 14, 2015 at about 3:10 pm local time, a 2012 amateur-built ZENITH CH 750, registered N1750Z, was substantially damaged in an accident during initial climb near Allentown, Pennsylvania (Allentown Queen City Muni airport). It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A partial loss of engine power due to the No. 1 spark plug being liberated from the cylinder head due to the stripped threads in the cylinder head. Contributing to the accident was the pilot’s decision to attempt to return to the airport while at a low altitude.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 14, 2015 · about 3:10 pm local time
- Place
- Allentown, Pennsylvania · Allentown Queen City Muni · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built ZENITH CH 750, built 2012
- Registration
- N1750Z · no longer on the register · serial 75-7859
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that, after takeoff, the airplane's engine lost partial power about 100 ft above ground level and that he then attempted to return to the airport. The pilot further stated that "the engine would not keep me flying and the airplane just fell into the forest." During the on-scene examination, the No. 1 spark plug was found missing from the cylinder head but still attached to the ignition lead. The threads were stripped out of the cylinder head. It is likely that the No. 1 spark plug was liberated from the cylinder head due to the stripped threads, which led to the partial loss of engine power.
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
- Powerplant sys/comp malf/fail during initial climb
- Loss of engine power (partial) during initial climb defining event
- Abrupt maneuver during emergency descent
- Aerodynamic stall/spin during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during uncontrolled descent
The NTSB's findings
- cause Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Malfunction
- cause Aircraft › Aircraft power plant › Ignition system › Spark plugs/igniters › Not specified
- factor Personnel issues › Action/decision › Info processing/decision › Decision making/judgment › Pilot
Pilot
- Certificate: sport pilot
- Ratings: single-engine land
- Flight time: 327.7 hours in all; 74 in this make and model
- Medical certificate: None
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 72 hours
- Last inspection: annual inspection, September 3, 2014
- Maximum gross weight: 1,320 lb
- Seats: 2
- Landing gear: fixed
- Engine: Chevrolet GO-140 (piston); 124 hours total
The flight
- Departed from: XLL Allentown PA at 3:05 pm
- Destination: XLL Allentown PA
- Flight plan: none
- Runway 25, 3,949 ft by 75 ft
Weather at the time
- Light: daylight
- Wind: from 250° at 6 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 82°F (28°C), dew point 63°F (17°C)
- Altimeter: 30.18 inHg
- Observation at 4:51 pm from KABE, 5 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 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.