WPR11CA072

NTSB accident investigation · Piper PA-18-150 · Pullman, WA · December 4, 2010

Accident · No injuriesData collectionFinal report
Date
December 4, 2010, 14:00 local (22:00 UTC)
Place
Pullman, WA
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N4100ZPiper PA-18-150
Defining event
Maneuvering-low-alt flying: Fuel related
Weather
Visual (VMC) · Day
Status
Completed · report April 12, 2011
Report
Approved by Office Director
NTSB office
Western Pacific Region
Parties
Spokane FSDO
FAA report
20101204052369A
Case key
77936

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 delayed application of carburetor heat while maneuvering, which resulted in a partial loss of engine power.

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.

Action: delayed actionPersonnel issues › Action/decision · PilotPiper PA-18-150: 11 casesAll aircraft: 894 casesProbable cause
Temp/humidity/pressure: conducive to carburetor icingEnvironmental issues › Conditions/weather/phenomena · Contributed to outcomePiper PA-18-150: 15 casesAll aircraft: 435 cases
Temp/humidity/pressure: conducive to carburetor icingEnvironmental issues › Conditions/weather/phenomena · Response/compensationPiper PA-18-150: 15 casesAll aircraft: 435 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.

Fuel relatedManeuvering-low-alt flyingPiper PA-18-150: 6 casesAll aircraft: 361 casesDefining event

Analysis

The pilot was maneuvering the airplane at a low altitude over open, snow-covered terrain, and noticed that the engine was beginning to lose power and running roughly. The airplane was starting to lose altitude and in response, he applied the carburetor heat and added full engine power. Just as the engine started to regain power, the main landing gear broke through the crusty top layer of the snow, slowing the airplane. The propeller contacted the snow and the pilot decreased the engine power and attempted to transition to a landing. The airplane nosed over inverted, resulting in substantial damage to the vertical stabilizer and both left wing lift struts. According to the pilot, with the exception of the accumulation of carburetor ice, there were no mechanical malfunctions or failures with the airframe or engine that would have precluded normal operation.

Factual narrative

The pilot, who was chasing coyotes at low level over open snow-covered terrain, noticed that the airplane's engine was beginning to lose power and run rough, and that the airplane was starting to lose altitude. He therefore applied carburetor heat and full power, but just as the engine started to regain power, the airplane's main wheels broke through the crusty top layer of the snow. The airplane then began to slow, and when its propeller contacted the snow, the pilot pulled the power back and attempted to transition to a landing. Although the pilot had the control stick all the way back, the airplane nosed over onto its back, resulting in damage to the vertical stabilizer and the bending of both left wing lift struts. According to the pilot, except for the accumulation of carburetor ice, there were no problems with the engine.

Aircraft

Registration
N4100Z
Reported as
Piper PA-18-150
Category
Airplane
Serial number
18-8114
Engine
Lycoming O-320 SERIES, 180 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Keith M. Kopf
Registered owner
Mountain Escape LLC
Airworthiness certificate
Standard, Normal
Departed
KPUW · Pullman, WA
Destination
KPUW · Pullman, WA

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
55
Injuries
None
Certificate
Private
Airplane ratings
Single-engine land, Single-engine sea
Medical
Class 3, Without waivers/limitations
Flight hours
1,315 total · 760 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
80° at 10 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
30 °F

Docket · 2

The files NTSB released with the investigation on December 20, 2010, on NTSB’s docket system: statements, records, photos and specialists’ reports. 504 KB 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 N4100Z · 1

Matched to the same aircraft by N-number and date.