WPR22LA177

NTSB accident investigation · Piper PA-12 · Enterprise, OR · May 14, 2022

Accident · No injuriesClass 3 · LimitedFinal report
Date
May 14, 2022, 14:30 local (21:30 UTC)
Place
Enterprise, OR · Wheat field
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N3960MPiper PA-12
Defining event
Takeoff: Powerplant sys/comp malf/fail
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Western Pacific Region
Parties
FAA-FSDO
FAA report
20220514007029A
Case key
105088

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

On this page

Probable cause

The inadequate maintenance and inspection of the crankshaft expansion plug, which resulted in the separation of the expansion plug from the crankshaft and the subsequent loss of oil and windshield obstruction during departure.

Findings · 1

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.

Engine (reciprocating): recip eng oil sysAircraft › Aircraft power plant · Incorrect service/maintenancePiper PA-12: 1 caseAll aircraft: 130 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 reported that shortly after departure, about 700 ft above ground level (agl), the windshield was sprayed with oil. He turned and entered the downwind leg of the traffic pattern and attempted to land on the runway. He reported that he was too high during the approach and aborted the landing. On the second attempt to land on runway 30, the oil spray was getting worse, and the pilot made a precautionary landing resulting in substantial damage to the fuselage. The postaccident examination of the airplane and interview with the mechanic revealed that the expansion plug was improperly installed and had separated from the end of the crankshaft, causing oil to exit through the propeller spinner resulting in the oil spray on the windshield.

Factual narrative

On May 14, 2022, about 1430 Pacific daylight time, a Piper PA-12 airplane, N3960M, was substantially damaged when it was involved in an accident near Enterprise, Oregon. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that shortly after departure from runway 30 at Enterprise Municipal Airport (8S4), Enterprise, Oregon, about 700 ft agl, the windshield was sprayed with oil. He turned and entered the downwind leg of the traffic pattern and attempted to land on runway 30. He reported that he was too high during the approach and aborted the landing. On the second attempt to land on runway 30, the oil spray was getting worse, and he stated that he “flew the plane onto the ground” east of the airport. The airplane impacted the ground resulting in damage to the fuselage. Postaccident examination of the engine revealed a loose crankshaft plug within the crankshaft. The pilot reported that about 50 flight hours before the accident, the airplane’s windshield was sprayed with oil when his friend was flying the airplane after an annual inspection during which the crankshaft plug was removed and reinstalled. The airplane landed safely, and it was determined that the expansion plug from the end of the crankshaft separated, causing oil to exit through the propeller spinner. The mechanic who performed the annual inspection reinstalled the expansion plug and the airplane operated about 39 hours before the accident flight. The FAA conducted an interview with the mechanic and it was determined that improper tools and technique were used when reinstalling the expansion plug. On both occasions, no record of reinstalling the expansion plug was added to the maintenance records. The Lycoming Service Instruction No. 1583, “Front Expansion Plug Replacement,” (SI1583), provides detailed instruction and tooling required for the replacement of the front expansion plug.

Aircraft

Registration
N3960M
Reported as
Piper PA-12
Category
Airplane
Serial number
12-2843
Built
1947
Engine
Lycoming O-320-B3B, 160 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Registered owner
Rouse Kenneth L
Airworthiness certificate
Standard, Normal
Last inspection
Annual · October 20, 2021 · 39 hours before
Airport
8S4 · Enterprise Municipal Airport, runway 30, 2,850 × 50 ft, asphalt

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
45
Injuries
None
Certificate
Student
Medical
Class 3, Without waivers/limitations
Seat
Front
Flight hours
7.6 total

Weather

Conditions
Visual (VMC) · Day
Visibility
10 statute miles
Lowest ceiling
5,000 ft broken
Temperature
55 °F, dew point 43 °F
Altimeter
30.14 inHg
Icing
Unknown
Turbulence
Unknown
Observed at
KJSY, 3 nm away
METAR
KJSY 142135Z AUTO 10SM SCT020 SCT025 BKN050 13/06 A3014 RMK AO2 T01300058 TSNO

Docket · 7

The files NTSB released with the investigation on April 10, 2024, on NTSB’s docket system: statements, records, photos and specialists’ reports. 6.4 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 N3960M · 1

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