ANC19LA054

NTSB accident investigation · Piper PA 18 · Beluga, AK · September 23, 2019

Accident · No injuriesClass 3 · LimitedFinal report
Date
September 22, 2019, 16:30 local (Sep 23, 2019, 00:30 UTC)
Place
Beluga, AK
Injuries
2 uninjured
Damage
Substantial damage
Phase of flight
Initial climb
Aircraft
N7071BPiper PA 18
Defining event
Initial climb: Loss of lift
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Alaska Regional Office
Parties
FAA Polaris CMO
FAA report
20190922018229A
Case key
100338

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 decision to perform a takeoff with an overweight float-equipped airplane, which resulted in diminished climb performance.

Findings · 4

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.

Runway/land/takeoff/taxi surfaceEnvironmental issues › Physical environment · Contributed to outcomePiper PA-18: 3 casesAll aircraft: 253 casesProbable cause
Performance/control parameters: climb rateAircraft › Aircraft oper/perf/capability · Not attained/maintainedPiper PA-18: 1 caseAll aircraft: 265 casesProbable cause
Aircraft capability: maximum weightAircraft › Aircraft oper/perf/capability · Capability exceededPiper PA-18: 1 caseAll aircraft: 152 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 private pilot performed a takeoff in his float-equipped airplane from a small lake with one passenger. The pilot estimated the lake to be 750 ft long, the weight of the airplane at 1,716 lbs, and the wind to be light and variable between 3 and 8 knots. He applied full power with one notch of extended flaps. At 40 mph, he extended the flaps another notch and the airplane lifted off the water, but it was unable to climb. The pilot and passenger stated that they did not observe or hear any abnormal engine indications. According to the pilot, the airplane descended to the ground beyond the lake, and the right float and wing impacted the ground. The airplane sustained substantial damage to the fuselage and right wing. The night of the accident, the pilot stated that he overloaded the airplane with moose meat and was forced to land after takeoff; he later stated that he did not know what caused the lack of climb performance, but “maybe it was a lack of engine power.” Additionally, he reported that he estimated the meat’s weight without weighing it, but he was confident that, including the load, the airplane’s takeoff weight was within the maximum gross weight limit, which was 1,760 lbs. The investigation was unable to determine the actual takeoff weight of the airplane due to the remote location of the accident and inaccessibility of the evidence. Postaccident engine examination and an engine test run revealed no anomalies that would have prevented normal operation. Given the pilot’s initial statement that the airplane was overloaded, his failure to weigh the load, and no evidence of engine anomalies, it is likely that the moose meat weighed more than the pilot estimated and that the airplane was overweight during the takeoff from the small lake.

Factual narrative

On September 22, 2019, about 1630 Alaska daylight time, a float-equipped Piper PA-18, N7071B, was substantially damaged when it was involved in an accident near Beluga, Alaska. The private pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that, on the day of the accident, he and the passenger harvested a moose on a small lake that he estimated to be 750 ft in length and decided to use the float plane to shuttle the meat to their hunting camp on another lake. Before loading the meat, the pilot flew multiple passes over the small lake and observed no hazards. He then performed a confined area landing and a practice takeoff without the load to assess the hazards and wind conditions. He observed light and variable winds from 3 to 8 knots and no problem taking off within the short distance. The passenger stated that there was a headwind during the practice takeoff and no wind after the accident, and they loaded a portion of the meat in the belly pod and the floats. The pilot stated that he was experienced at estimating meat weight and that the airplane’s takeoff weight was below the maximum gross weight of 1,760 lbs. According to the pilot, there were no known mechanical issues with the airplane and the runup was normal. He conducted the takeoff from the lake with one notch of flaps extended. At 40 mph indicated airspeed, he extended another notch of flaps, and the floatplane successfully lifted off the water but was unable to climb. The pilot and passenger stated that they did not observe or hear any abnormal engine indications. The airplane descended to the ground beyond the lake, the right float and wing impacted the ground, and the airplane sustained substantial damage to the fuselage and right wing. The night of the accident, the pilot stated that he overloaded the airplane with the moose meat and was forced to land after takeoff; he later stated that he did not know what caused the lack of climb performance, but “maybe it was a lack of engine power.” The pilot provided the estimated weights as: crew 365 lbs, fuel 78 lbs, meat in belly pod 60 lbs, meat in floats 50 lbs, and survival bag 9 lbs. The total estimated weight was 1,716 lbs, and the allowable maximum gross weight of the airplane was listed as 1,760 lbs in the airplane’s most recent weight and balance document. The passenger stated that there were no mechanical issues with the airplane and that the only abnormalities he observed during the takeoff were the lack of climb performance and the engine going quiet immediately before impact. Postaccident examination of the engine revealed that the engine was intact with no loose lines, leaks, or impact damage. Engine control continuity was established. The propeller was attached and turned smoothly by hand, and the blades were undamaged. The ignition harness and spark plugs were intact. A fuel sample obtained from the fuel filter was consistentwith avgas and free of contamination. There were no abnormalities noted in the air intake or exhaust system. During a test run, the engine was started and advanced to 2,300 rpm with no anomalies noted. The investigation did not obtain the actual weight of the airplane’s contents due to the remote location of the accident.

Aircraft

Registration
N7071B
Reported as
Piper PA 18 (150)
Category
Airplane
Serial number
18-5146
Built
1956
Airframe hours
2,600
Engine
Lycoming O-320-B2B, 160 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Airworthiness certificate
Standard, Normal
Last inspection
Annual · June 5, 2019
Departed
Beluga, AK
Destination
Beluga, AK

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
34
Injuries
None
Certificate
Private
Airplane ratings
Single-engine sea, Single-engine land
Medical
Class 3, Without waivers/limitations
Seat
Front
Flight hours
300 total

Weather

Conditions
Visual (VMC) · Day
Wind
40° at 4 knots
Visibility
10 statute miles
Lowest ceiling
14,000 ft broken
Temperature
54 °F, dew point 37 °F
Altimeter
29.55 inHg
Observed at
PANC, 36 nm away

Docket · 6

The files NTSB released with the investigation on November 4, 2021, on NTSB’s docket system: statements, records, photos and specialists’ reports. 53.2 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 N7071B · 1

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