ANC21LA017

NTSB accident investigation · Maule M-6-235 · Tyonek, AK · February 13, 2021

Accident · Minor injuriesClass 4 · LimitedFinal report
Date
February 13, 2021, 13:00 local (22:00 UTC)
Place
Tyonek, AK · Capps Glacier
Injuries
2 minor
Damage
Substantial damage
Phase of flight
Landing
Aircraft
N56517Maule M-6-235
Defining event
Landing: Loss of control on ground
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 4 - Basic report with no Prelim publish
NTSB office
Alaska Regional Office
Parties
FAA
FAA report
20210213000539A
Case key
102639

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 selection of unsuitable terrain for landing, which resulted in the airplane encountering deep snow and coming to rest inverted.

Findings · 5

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: landing flareAircraft › Aircraft oper/perf/capability · Not attained/maintainedMaule M-6-235: 1 caseAll aircraft: 1,285 casesProbable cause
Use of equip/info: aircraft controlPersonnel issues › Task performance · PilotMaule M-6-235: 7 casesAll aircraft: 9,295 casesProbable cause
Runway/land/takeoff/taxi surface: soft surfaceEnvironmental issues › Physical environment · Effect on operationMaule M-6-235: 1 caseAll aircraft: 264 cases

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 initially reported that before landing on a snow-covered glacier, he intended to fly a low pass over the snow-covered site and briefly touchdown to determine the condition of the snowpack, a maneuver commonly known as dragging the landing site. He said that during a second downhill pass over the site, he inadvertently allowed the tailwheel-ski equipped airplane to slow while attempting to “set the track more fully”. He added that, he mis-judged the snow depth and allowed the airplane to slow too much. Subsequently, the ski tips dug into the snow and the airplane came to rest inverted. The airplane sustained substantial damage to the fuselage, the wings, and the empennage. The pilot initially reported there were no preimpact mechanical failures or malfunctions with the airframe and engine that would have precluded normal operation. The pilot later reported that he believed the brake calipers had obstructed the movement of the skis. Two witness marks were observed on the skis that indicated the brake calipers had impacted the skis. A Federal Aviation Administration (FAA) aviation safety inspector (airworthiness) examined the airplane and stated that there were no preimpact mechanical failures or malfunctions found with the airplane. Based on the available evidence, it is likely that the damage to the skis from the brake calipers were from impact damage.

Aircraft

Registration
N56517
Reported as
Maule M-6-235
Category
Airplane
Serial number
7450C
Built
1983
Airframe hours
2,363.9
Engine
Lycoming IO-540-W1A5, 235 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Paul Andrews
Airworthiness certificate
Standard, Normal
Last inspection
Annual · June 28, 2020
Departed
BCV · Birchwood, AK
Destination
Same as departure
Equipment
Handheld GPS, Electronic multifunction display

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
53
Injuries
Minor
Certificate
Private
Airplane ratings
Single-engine sea, Single-engine land
Medical
Class 3, Without waivers/limitations
Last flight review
September 28, 2020
Seat
Left
Flight hours
1,998 total · 1,998 as pilot in command · 10 in the last 90 days · 6 in the last 30 days · 3 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
30° at 5 knots
Visibility
10 statute miles
Temperature
16 °F, dew point 7 °F
Altimeter
29.83 inHg
Observed at
PANC, 58 nm away
METAR
PANC 132153Z 03005KT 10SM FEW110 M09/M14 A2983 RMK AO2 SLP106 T10941139

FAA reports on this event · 1

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