CEN19LA224

NTSB accident investigation · Piper PA18 · Osceola, WI · July 14, 2019

Accident · No injuriesClass 3 · LimitedFinal report
Date
July 14, 2019, 13:15 local (18:15 UTC)
Place
Osceola, WI
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Takeoff
Aircraft
N6983BPiper PA18
Defining event
Takeoff: Flight control sys malf/fail
Weather
Visual (VMC) · Day
Status
Completed
Report
Approved by Office Director
Investigation class
Class 3
NTSB office
Central Region
Parties
FAA FSDO, Piper Aircraft
FAA report
20190714011749A
Case key
99834

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 failure of the right horizontal stabilizer during takeoff, resulting in a loss of control and forced landing. Contributing to the accident was the installation of an unapproved stabilizer frame and failure of maintenance personnel to identify deterioration of the stabilizer during routine maintenance.

Findings · 2

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.

Empennage structure: horizontal stabilizerAircraft › Aircraft structures · Fatigue/wear/corrosionPiper PA-18A 150: 1 caseAll aircraft: 23 casesProbable cause
Maintenance: unauthorized maint/repairPersonnel issues › Task performance · Maintenance personnelPiper PA-18A 150: 1 caseAll aircraft: 14 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

Upon takeoff, the pilot heard a “bang” and could not control the airplane. The pilot was able to get the wings level before the airplane hit the ground. The airplane bounced, went through a ditch, and came to rest inverted, resulting in substantial damage to the empennage. Examination of the airplane revealed a broken attachment fitting of the right horizontal stabilizer. The fabric covering was removed from the right and left stabilizers. The attachment corner of the right stabilizer frame was fractured. Pitting, multiple broken welds, and corrosion were found around the fracture. The right stabilizer frame had been fabricated and was not a Federal Aviation Adminstration/parts manufacturer approval-approved part. Maintenance records revealed that the stabilizer assembly had been removed for inspection, refurbished, and replaced multiple times. The most recent maintenance was performed about 4 months prior to the accident, when an annual inspection was completed and new sleeves for the forward attachment points were fabricated and installed on the stabilizer assembly.

Factual narrative

On July 14, 2019, about 1315 central daylight time, a Piper PA18-150, N6963B, was substantially damaged when it was involved in an accident near Osceola, Wisconsin. The commercial pilot was not injured. The glider towing flight was conducted under the provisions Title 14 Code of Federal Regulations Part 91. The pilot reported that he had three non-eventful glider tows prior to the accident flight. On the fourth glider tow of the day, the pilot added full power for takeoff and became airborne at 55 mph indicated airspeed. About 5 to 15 feet off the ground, the pilot heard a sudden '"bang," and the nose of the airplane pitched up about 40ºand rolled right about 45º. The aircraft seemed uncontrollable with rudder. The pilot was able to get the wings level before the airplane hit the ground hard. The pilot reduced the power to idle and applied brakes. The airplane skidded between two electric poles, bounced onto a road, went through a ditch, and came to rest inverted. The empennage sustained substantial damage. The glider being towed had released the tow rope and landed uneventfully nearby. Examination of the airplane revealed a broken attachment fitting of the right horizontal stabilizer. The Ceconite fabric covering was removed from the right and left stabilizers. The attachment corner of the right stabilizer frame was fractured. Pitting, multiple broken welds, and corrosion were found around the fracture. The right stabilizer frame had been fabricated and was not a Federal Aviation Adminstration/parts manufacturer approval-approved part. Review of maintenance records revealed that the stabilizer assembly had been removed for inspection, refurbished, and replaced multiple times. The most recent maintenance was performed on March 1, 2019, when an annual inspection was completed and new sleeves for the forward attachment points were fabricated and installed on the stabilizer assembly.

Aircraft

Registration
N6983B
Reported as
Piper PA18 (150)
Category
Airplane
Serial number
18-5105
Built
1956
Airframe hours
7,040
Engine
Lycoming O-320 SERIES, 180 horsepower, reciprocating
Damage
Substantial damage
Flight
Personal · Part 91
Operator
Red Wing Soaring Association
Registered owner
Red Wing Soaring Association
Airworthiness certificate
Standard, Normal
Last inspection
Annual · March 1, 2019 · 51 hours before
Departed
OEO · Osceola, WI
Destination
OEO · Osceola, WI
Airport
OEO · L O Simenstad Muni, runway 10, 2,100 × 75 ft, grass/turf
Equipment
None

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
50
Injuries
None
Certificates
Private, Commercial
Medical
Class 2, With waivers/limitations
Last flight review
November 25, 2018
Seat
Left
Restraint
4-point
Flight hours
1,000 total · 250 in this make and model · 36 in the last 90 days · 11 in the last 30 days · 1 in the last 24 hours

Weather

Conditions
Visual (VMC) · Day
Wind
180° at 8 knots
Visibility
10 statute miles
Lowest ceiling
3,800 ft broken
Temperature
84 °F, dew point 72 °F
Altimeter
30.05 inHg
Observed at
OEO

Docket · 3

The files NTSB released with the investigation on January 26, 2022, on NTSB’s docket system: statements, records, photos and specialists’ reports. 13.8 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 N6983B · 1

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