ANC97TA148

NTSB accident investigation · Piper PA-18-150 · Saint Mary'S, AK · September 13, 1997

Accident · No injuriesFinal report
Date
September 13, 1997, 13:00 local (21:00 UTC)
Place
Saint Mary'S, AK
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N7054Piper PA-18-150
Weather
Visual (VMC) · Day
Status
Completed · report November 6, 1998
Report
Approved by Office Director
NTSB office
Alaska Regional Office
FAA report
19970913026609A
Case key
3085

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 excessive pressure in the brake system resulting from heating of the recently serviced hydraulic fluid in the brake master cylinders, and the resultant locked brakes and inability to maintain directional control of the airplane.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Airframe/component/system failure/malfunctionLanding - flare/touchdown
Landing gear,normal brake system - pressure excessiveCause
Landing gear,normal brake system - lockedCause
Directional control - not possiblePilot in commandCause
Nose overLanding - roll

Analysis

The 29-inch tundra tire equipped airplane was being landed on a wet, sandy, gravel bar. The pilot stated that the back seat heater had been blowing hot air on the brake master cylinders, which had just been serviced. At touchdown, the airplane began to nose over. The pilot attempted to add power and keep the tail down with airflow, but the airplane continued over onto its back. Skid marks were measured for 154 feet from the touchdown point.

Factual narrative

On September 13, 1997, at 1300 Alaska daylight time, a tundra tire equipped Piper PA-18-150 airplane, N7054, was substantially damaged when it nosed over during landing on a gravel bar, 10 miles east of Saint Mary's, Alaska. The commercial certificated pilot was uninjured. The airplane was operated by the State of Alaska, Department of Public Safety. The flight was conducted under 14 CFR Part 91 as a public use flight. Visual meteorological conditions prevailed at the time of the accident, and a flight plan was filed with the operator. The airplane was accompanied by another public use airplane.

The pilot stated that he was landing on a gravel bar. He stated to the NTSB investigator that the Gar-Aero 29 inch tundra tires contacted soft, wet sand, and the airplane began to nose over. He applied power to attempt to maintain airflow across the tail, but the airplane nosed over onto its back.

In his pilot/operator report, the pilot indicated the brakes appeared locked, and there were skid marks in the sand for 154 feet. The pilot also indicated that hot air from the back seat heater hose was blowing on the brake master cylinders, which had just been serviced.

Aircraft

Registration
N7054
Reported as
Piper PA-18-150
Category
Airplane
Serial number
18-8915
Airframe hours
7,635
Engine
Lycoming O-320-B2B, 160 horsepower, reciprocating
Damage
Substantial damage
Flight
Public aircraft · Part 91
Registered owner
Alaska Dept Public Safety
Airworthiness certificate
Standard, Normal
Last inspection
Annual · July 28, 1997 · 62 hours before
Departed
BET · Bethel, AK
Destination
BET · AK
Flight plan
Company VFR

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
39
Certificate
Commercial
Airplane ratings
Single-engine land, Single-engine sea
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--no waivers/lim.
Seat
Front
Flight hours
3,000 total · 2,900 in this make and model · 300 in the last 90 days · 100 in the last 30 days · 5 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
90° at 2 knots
Visibility
40 statute miles
Lowest ceiling
4,000 ft overcast
Temperature
50 °F
Altimeter
29.00 inHg

FAA reports on this event · 1

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