- Date
- August 18, 2025, 13:30 local (17:30 UTC)
- Place
- Monroe, MI
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Landing
- Aircraft
- N4431UHelio H-391B
- Defining event
- Landing-flare/touchdown: Loss of control on ground
- Weather
- Visual (VMC) · Day
- Status
- Completed · report January 9, 2026
- Report
- Approved by Office Director
- Investigation class
- Class 4 - Basic report with no Prelim publish
- NTSB office
- Central Region
- Parties
- FAA
- FAA report
- 20250818013389A
- Case key
- 200814
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The pilot’s failure to maintain directional control during the landing roll with a crosswind.
Findings · 3
NTSB’s coded findings. Those marked are part of the probable cause; the rest are factors or other findings. Under each, the cases with the same finding.
Sequence of events
The events NTSB coded, in order, by phase of flight. The defining event is the one that best describes the accident. Under each, the cases with the same event anywhere in their sequence.
Analysis
The pilot reported that while landing his tailwheel airplane in a crosswind, the airplane bounced upon touchdown. The right wing lifted, the airplane drifted down the runway on the left wheel, and the airplane exited the runway into the grass. The left wheel dug into the grass and the airplane pivoted. During the accident sequence, the left landing gear separated from the fuselage, and the left wing struck the ground. The left wing was substantially damaged. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. At the time of the accident, the pilot was landing the airplane on runway 03 with wind from 100° at 10 knots gusting 15 knots.
Aircraft
- Registration
- N4431U
- Reported as
- Helio H-391B
- Category
- Airplane
- Serial number
- 091
- Built
- 1958
- Airframe hours
- 2,385
- Engine
- Lycoming GO435C2B2-6, 260 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · August 8, 2025 · 14 hours before
- Departed
- 3NP · Napolean, MI
- Destination
- TTF · Monroe, MI
- Airport
- TTF · Custer Airport, runway 03, 4,997 × 100 ft, concrete
- Equipment
- None
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 66
- Injuries
- None
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Medical
- Class 3, With waivers/limitations
- Last flight review
- September 13, 2024
- Seat
- Left
- Restraint
- 3-point
- Flight hours
- 329 total · 12 in this make and model · 12 in the last 90 days · 12 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 100° at 10 knots, gusting 15
- Visibility
- 10 statute miles
- Lowest ceiling
- 3,200 ft broken
- Temperature
- 75 °F, dew point 63 °F
- Altimeter
- 30.18 inHg
- Observed at
- KTTF
- METAR
- KTTF 181735Z AUTO 10010G15KT 070V130 10SM BKN032 OVC038 24/17 A3018
Docket · 2
The files NTSB released with the investigation on January 9, 2026, on NTSB’s docket system: statements, records, photos and specialists’ reports. 3.3 MB in all.
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N4431U · 2
Matched to the same aircraft by N-number and date.