CHI08LA123

NTSB accident investigation · Dickenson Bathtub · Broadhead, WI · May 5, 2008

Accident · FatalLimited investigationFinal report
Date
May 5, 2008, 17:00 local (22:00 UTC)
Place
Broadhead, WI
Injuries
1 fatal
Damage
Destroyed
Phase of flight
Approach
Aircraft
N538Dickenson Bathtub
Defining event
Approach-VFR pattern final: Aerodynamic stall/spin
Weather
Visual (VMC) · Day
Status
Completed · report July 28, 2009
Report
Approved by Office Director
Parties
FAA-Milwaukee FSDO
FAA report
20080505835559A
Case key
68004

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The pilot's failure to maintain adequate airspeed during approach, which resulted in an aerodynamic stall.

Findings · 2

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.

Performance/control parameters: airspeedAircraft › Aircraft oper/perf/capability · Not attained/maintainedDickenson BATHTUB: 1 caseAll aircraft: 1,681 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · PilotDickenson BATHTUB: 1 caseAll aircraft: 9,295 casesProbable cause

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 airplane was destroyed when it impacted terrain following a loss of control on final approach to land. The flight was the pilot's first flight in the airplane. A witness reported seeing the airplane as it turned from a left base leg of the airport traffic pattern to final approach. The witness reported that the airplane's bank angle increased during the turn to correct for wind drift. It then stalled and entered a spin. Another witness also reported that he believed the accident was the result of a stall/spin. Neither witness reported hearing any engine malfunctions. No preimpact mechanical deficiencies were found with the airplane.

Factual narrative

History of flight

On May 5, 2008, about 1700 central daylight time, an amateur-built Dickenson Bathtub, N538, was destroyed when it impacted terrain following a loss of control on final approach to land on runway 03 at the Broadhead Airport, Broadhead, Wisconsin. The private pilot was fatally injured. Visual meteorological conditions prevailed for the 14 CFR Part 91 flight. No flight plan was filed. The local flight originated at an unconfirmed time.

A witness reported seeing the airplane during its approach to the airport. He stated that as the airplane made a left turn from the base leg of the approach to the final approach he noticed that the wind was drifting the airplane toward some houses. He stated that he saw the airplane's turn tighten, and then the airplane entered a stall/spin. It subsequently impacted the ground. He estimated that the airplane's altitude was about 300 feet above the ground when it entered the spin. He stated that he heard no engine malfunctions. He stated that the accident flight was the pilot's first flight in the airplane.

Another witness who has been a certified flight instructor since 1982 reported that he believed the accident was the result of a stall/spin. He noted that the engine was running fine and seemed "ok" all the way to the ground.

Personnel information

The pilot, age 77, held a Federal Aviation Administration private pilot certificate with single engine land and sea ratings. He also held a third class medical certificate issued January 31, 2008. The medical certificate listed a limitation that the pilot have glasses available for near vision. FAA records indicate that the pilot had accumulated a total of 1,400 flight hours as of the date of his most recent medical examination. No further pilot flight records were obtained.

Aircraft information

The airplane was an amateur-built replica of a 1924 Dormoy Bathtub. It had a single strut braced fabric covered parasol mounted wing. The fuselage consisted of an open pilot enclosure with a single tubular structure running along the bottom of the fuselage and aft to the tail surfaces. Two additional tubular supports ran from the trailing edge of the wing to the top of the vertical tail.

Meteorological information

At 1656, the weather conditions at the Monroe Municipal Airport, about 9 miles west of the accident site, were: Wind 260 degrees at 13 knots gusting to 16 knots; visibility 10 miles; scattered clouds at 10,000 feet; temperature 22 degrees Celsius; dew point -4 degrees Celsius; altimeter setting 19.98 inches of mercury.

Airport information

The Broadhead Airport was a privately owned airport and had 3 turf runways. The runway in use at the time of the accident was Runway 03 which was 1,480 feet long and 100 feet wide.

Wreckage and impact information

The airplane came to rest in a nose low position. The aft fuselage tubing structure was bent forward and upward in relation to the fuselage tub. The right wing and right landing gear were crushed rearward. The left wing remained intact. Examination of the airplane did not reveal any pre-existing deficiencies.

Medical and pathological information

An autopsy of the pilot was performed by the University of Wisconsin, School of Medicine. The report stated that the pilot perished as a result of the aircraft collision.

A Final Forensic Toxicology Fatal Accident Report listed Naproxen detected in the pilot's urine.

Aircraft

Registration
N538
Reported as
Dickenson Bathtub
Category
Airplane, amateur-built
Serial number
101
Airframe hours
1
Engine
Heath Avn B4, 25 horsepower, reciprocating
Damage
Destroyed
Flight
Personal · Part 91
Airworthiness certificate
Special, Experimental (Special)
Last inspection
Condition · August 31, 2007 · 1 hours before
Departed
C37 · Broadhead, WI
Airport
C37 · Broadhead Airport, runway 03, 1,480 × 100 ft, grass/turf

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
77
Injuries
Fatal
Certificate
Private
Airplane ratings
Single-engine land, Single-engine sea
Medical
Class 3, With waivers/limitations
Seat
Center
Toxicology
Performed
Flight hours
1,400 total · 1 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
260° at 13 knots, gusting 16
Visibility
10 statute miles
Lowest ceiling
None
Temperature
72 °F, dew point 25 °F
Altimeter
30.00 inHg
Observed at
EFT, 9 nm away

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.