# NTSB CEN23LA372: Pietenpol Aircamper, N929DH, Hanover, IL, August 20, 2023

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: August 20, 2023, 08:00 local (13:00 UTC)
- Place: Hanover, IL
- Coordinates: 42.289253, -90.293294 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=42.2893&lon=-90.2933&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report September 30, 2025
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: FAA FSDO
- SAIBs cited in the narratives: [SAIB CE-09-35](https://openairdocs.org/saib/CE-09-35) (OpenAirDocs)
- NTSB case key (mKey): 192911
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN23LA372
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192911/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192911
- Page: https://openairdocs.org/ntsb/CEN23LA372

## Probable cause

The pilot’s exceedance of the airplane’s critical angle of attack, which resulted in an aerodynamic stall during an attempted forced landing at low altitude. Contributing to the accident was the loss of engine power for undetermined reasons.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=05629G1), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)
- [Engine (reciprocating)](https://openairdocs.org/ntsb-findings/01058500): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-findings/01058500/cases.md?model=05629G1), [All aircraft, 497 cases](https://openairdocs.org/ntsb-findings/01058500/cases.md)
- [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=05629G1), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md)
- [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=05629G1), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-events/000/sequence.md?model=05629G1), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05629G1), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Emergency descent: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Helsper Daniel W PIETENPOL AIRCAMPER, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=05629G1), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md)

## Analysis

The pilot reported that, about 45 minutes after takeoff, the engine began to lose power and he attempted a forced landing to a hayfield. As the airplane descended toward the hayfield, the pilot allowed the airspeed to decrease. The airplane stalled and impacted a cornfield, resulting in substantial damage to the fuselage and both wings. Postaccident examination of the fuel system revealed that the fuel cap was loosely installed, and the sight glass indicated the fuel tank was nearly full. Fuel samples from the gascolator contained an unidentified white particulate, with no water detected. The throttle cable was disconnected at the carburetor; this was likely due to the fuselage separation during impact. Examination of the engine revealed no evidence of pre-impact failures or malfunctions that would have precluded normal operation. Examination of the fuel system revealed only a small amount of fuel in the carburetor bowl; however, it could not be determined whether that resulted from impact or an in-flight lack of fuel delivery to the carburetor. Although the FAA’s Carburetor Icing Chart revealed that the reported temperature and dew point conditions were conducive to the formation of carburetor icing at glide and cruise power, the investigation could not determine that the loss of engine power resulted from the formation of carburetor icing.

## Factual narrative

On August 20, 2023, about 0800 central daylight time, a Pietenpol Aircamper airplane, N929DH, was substantially damaged when it was involved in an accident near Hanover, Illinois. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the morning of the flight he had fueled the airplane with nonethanol MOGAS (automotive gasoline) to a full capacity of 11 gallons and departed Monticello Regional Airport (MXO), Monticello, Iowa, destined for Poplar Grove Airport (C77), Poplar Grove, Illinois. After about 45 minutes of flight, the engine began to lose power. He attempted a forced landing to a hayfield, but the airplane impacted terrain in a cornfield short of the intended forced landing location. The airplane sustained substantial damage to both wings and the fuselage. Postaccident examination of the fuel system revealed that the fuel cap was loosely installed, and the sight glass indicated that the fuel tank was nearly full. The fuel shutoff valve was found in the OFF position; the pilot reported that he had shut the fuel off after the forced landing. Fuel samples from the gascolator contained unidentified white particulate with no water detected. The carburetor bowl contained a small amount of fuel, and about 3 ounces of fuel was observed in the intake pipe after carburetor removal. The carburetor was disassembled and found to be unremarkable, other than slight corrosion noted on the gas adjustment valve needle. The airplane’s modified Ford Model A engine was intact, and the throttle cable was disconnected at the carburetor with the cable pinch bolt still located in the throttle arm. Thumb compression was obtained on all four cylinders, the spark plugs were unremarkable, and a test of the top magneto produced spark on all leads. Postaccident examination of the engine revealed no mechanical malfunctions or failures that would have precluded normal operation. The carburetor icing probability chart from FAA Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, supported a potential for carburetor icing at glide and cruise power at the temperature and dew point reported at the time of the accident.

## Aircraft

- Registration: [N929DH](https://openairdocs.org/aircraft/N929DH), registered now, S/N 001, built 2010 (OpenAirDocs)
- Reported make and model: PIETENPOL AIRCAMPER
- Registry model: [Helsper Daniel W PIETENPOL AIRCAMPER](https://openairdocs.org/model/helsper-daniel-w-pietenpol-aircamper) (registry code 05629G1) (OpenAirDocs)
- Registry engine: [Ford CONVERSION](https://openairdocs.org/engine/ford-conversion) (registry code 26701, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 001
- Year built: 2010
- Airframe hours: 362
- Engines: FORD Model A 60 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Condition, August 20, 2022
- Departed: MXO, Monticello, IA
- Destination: C77, Poplar Grove, IL
- Airport: n/a
- Equipment: Electronic flight bag or handheld device, Handheld GPS

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 69; injuries: none; commercial, private; airplane ratings: single-engine land; medical: basicmed, with waivers/limitations; last flight review April 24, 2023; seat: rear; restraint: 5-point; flight hours: 1,635 total, 500 in this make and model, 1,480 as pilot in command, 16 in the last 90 days, 14 in the last 30 days, 0 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 7 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 77 °F
- Altimeter: 30.09 inHg
- Observed at: KDBQ, 19 nm away
- METAR: KDBQ 201553Z 02007KT 10SM CLR 29/25 A3009 RMK AO2 SLP181 T02940250 $

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 20230820015989A](https://openairdocs.org/incident/20230820015989A), Aug 20, 2023: Helsper Daniel W PIETENPOL AIRCAMPER, Hanover, IL, Substantial damage. Pilot departed monticello regional airport (mxo) enroute to poplar grove airport (C77) on a pleasure trip. About 45 minutes into the flight, the engine began…

## Docket (6 files)

The files NTSB released with the investigation on September 30, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192911. 9.4 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19332654&FileExtension=pdf&FileName=6120_1__Redacted-Rel.pdf
- Pilot's statement (item 2, PDF, 1 page, 748 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19333237&FileExtension=pdf&FileName=Pilot%20statement_Redacted-Rel.pdf
- Maintenance records (item 3, PDF, 1 page, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19333330&FileExtension=pdf&FileName=Log%20Entry_Redacted-Rel.pdf
- Photos (item 4, PDF, 5 pages, 4 photos, 2.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19336858&FileExtension=pdf&FileName=photos-Rel.pdf
- FAA inspector's statement (item 5, PDF, 1 page, 82 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19333159&FileExtension=pdf&FileName=Preliminary%20Inspector%20statement%20N929DH-Rel.pdf
- Carburetor icing probability graph (item 6, PDF, 1 page, 335 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19331928&FileExtension=pdf&FileName=Carburetor%20Icing%20Probability%20Graph%20(CEN23LA372)-Rel.pdf

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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