PIPER PA32R

Attalla, AL — November 27, 2023

Event Information

DateNovember 27, 2023
Event TypeACC
NTSB NumberERA24FA050
Event ID20231128193432
LocationAttalla, AL
CountryUSA
Coordinates33.99425, -86.16008
AirportMountainous Terrain with Trees
Highest InjuryFATL

Aircraft

MakePIPER
ModelPA32R
CategoryAIR
FAR Part091
Aircraft DamageDEST

Conditions

Light ConditionNITE
WeatherVMC

Injuries

Fatal1
Serious0
Minor0
None0
Total Injured1

Probable Cause

The undetected wear of both pawl retaining rivets of the left magneto impulse coupling and fatigue failure of one pawl retaining rivet, which led to cascading fractures of the second pawl retaining rivet, left gear retainer assembly, and gear teeth of multiple gears in the accessory section of the engine and resulted in a loss of engine power. Contributing to the accident was the lack of current information available to the pilot regarding the status of a nearby airport’s closed runways.

Full Narrative

HISTORY OF FLIGHTOn November 27, 2023, about 1748 central standard time, a Piper PA-32R-301T airplane, N4187Q, was destroyed when it was involved in an accident near Attalla, Alabama. The private pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight.

The pilot was on an instrument flight rules clearance from Scott Municipal Airport (SCX), Oneida, Tennessee, to H L Sonny Callahan Airport (CQF), Fairhope, Alabama.

According to FAA ADS-B data and air traffic control audio information, after takeoff the airplane proceeded toward the destination while the pilot established contact with several air traffic control facilities appropriate for the route of flight. ADS-B data indicated that after 1743:03, the airplane began a descent that was not instructed by the controller or broadcast by the pilot. At that time, the flight was about 4 nm north-northeast from the approach end of runway 18 at Northeast Alabama Regional Airport (GAD), Gadsden, Alabama, flying on a south-southwesterly track.

At 1743:35, while in contact with the South Radar position of the Birmingham Airport Traffic Control Tower, the pilot advised the controller, “I have lost um my rpm on my engine and so um I am declaring an emergency.” The controller advised the pilot that Albertville Regional Airport – Thomas J Brumlik Field (BFZ), Albertville, Alabama, was to his right at 12 miles and Birmingham-Shuttlesworth International Airport (BHM), Birmingham, Alabama, “would be twelve o’clock and about three zero miles say intentions.” ADS-B data reflected that about the time the controller provided the distances to the two airports, the airplane was actually located about 15 nm from the center of BFZ and about 45 nm from the center of BHM. Shortly after the pilot declared an emergency, the airplane turned right to a westerly track. While on that track, the pilot recognized that he was close to GAD and asked about it, but the controller advised him that the longer runway (6/24) was closed and the shorter runway (18/36) did not have any runway lights, “so that not gonna be feasible for us.” The pilot again questioned the controller about GAD and was again informed of the runway closure, and that runway 18/36 “has got work on it as well with no lights.”

At 1744:58, when the flight was about 3 nm nearly due north from the approach end of runway 18 at GAD and 15 nm east-northeast from the center of 20A, the pilot asked the controller for a heading to the “closest one” and was given vectors to 20A. The airplane remained on a westerly track until 1745:43. At that time, while flying at 3,150 ft mean sea level (msl), the airplane turned left to a south-southwesterly track. The airplane continued descending on that same track when, at 1746:04, the pilot informed the controller that the airplane was at 3,000 ft msl. About 26 seconds later, the pilot advised the controller that he did not have any airport in sight. The flight continued, and the last ADS-B target was at 1746:34, when the airplane was at 2,300 ft msl. At 1747:32, the controller advised the pilot that radar contact was lost and asked if the pilot had a nearby highway in sight, to which the pilot replied “I,” but the rest of the comment was unintelligible. At 1748:02, the pilot’s last recorded transmission advised the controller that he had a terrain warning, and the airplane was at 1,100 ft msl.

One witness, who was located about 1,083 ft north-northeast from the accident site, reported hearing an airplane flying low; the witness then heard an explosion and felt it shake the house. A second witness, who was located 2,020 ft northeast of the accident site, reported seeing a fireball after the accident.

Security cameras about 4,000 ft northwest of the accident site depicted the airplane flying from left to right, with a large fireball recorded at 1748:10. The videos did not contain sound.

The accident site was located about 3.7 nautical miles west-northwest from the center of GAD. AIRCRAFT INFORMATIONA factory-rebuilt engine equipped with a Slick by Champion model 6361 impulse coupling magneto in the left position was installed on the airplane on November 20, 2018, at airplane total time of 2214.0 hours. The magneto manufacturer called for a 500-hour inspection of the impulse coupling, as specified by Slick Service Bulletin SB1-86C. The 500-hour inspection required inspection of the impulse coupling pawl retaining rivets dimensionally and for looseness and any indications of movement.

A review of engine maintenance records revealed that on April 15, 2022, at a reported airframe total time of 3,197.9 hours (983.9 hours since engine rebuild), a 500-hour inspection of the left and right magnetos was performed. According to an electronic pilot logbook that was current as of about 5 days before the accident, the pilot had operated the airplane for about 300 hours since the 500-hour magneto inspection had been performed.

The airplane was equipped with an electrically-operated auxiliary fuel pump for use, in part, in case of failure of the engine-driven fuel pump, while the engine was equipped with two independent magnetos, each providing spark to one spark plug for each cylinder. Each magneto contained a gear retainer assembly with drive cushions and was installed onto the engine accessory case and driven by separate crankshaft idler gears. The left magneto also contained an impulse coupling, which was a mechanical device to assist in engine starting. At low cranking speed, the magneto impulse coupling would retard the magneto ignition timing and provide a brief acceleration that produced an intense spark for starting. After engine start, the impulse coupling would disengage and return the magneto to normal engine timing.

The airplane Pilot’s Operating Handbook and FAA-Approved Airplane Flight Manual checklists for loss of engine power in-flight and engine-driven fuel pump failure both instructed the pilot to turn on the electric fuel pump.

Based on pilot logbook information and ADS-B data, the airplane had been operated about 113 hours since the airplane’s last annual inspection. AIRPORT INFORMATIONA factory-rebuilt engine equipped with a Slick by Champion model 6361 impulse coupling magneto in the left position was installed on the airplane on November 20, 2018, at airplane total time of 2214.0 hours. The magneto manufacturer called for a 500-hour inspection of the impulse coupling, as specified by Slick Service Bulletin SB1-86C. The 500-hour inspection required inspection of the impulse coupling pawl retaining rivets dimensionally and for looseness and any indications of movement.

A review of engine maintenance records revealed that on April 15, 2022, at a reported airframe total time of 3,197.9 hours (983.9 hours since engine rebuild), a 500-hour inspection of the left and right magnetos was performed. According to an electronic pilot logbook that was current as of about 5 days before the accident, the pilot had operated the airplane for about 300 hours since the 500-hour magneto inspection had been performed.

The airplane was equipped with an electrically-operated auxiliary fuel pump for use, in part, in case of failure of the engine-driven fuel pump, while the engine was equipped with two independent magnetos, each providing spark to one spark plug for each cylinder. Each magneto contained a gear retainer assembly with drive cushions and was installed onto the engine accessory case and driven by separate crankshaft idler gears. The left magneto also contained an impulse coupling, which was a mechanical device to assist in engine starting. At low cranking speed, the magneto impulse coupling would retard the magneto ignition timing and provide a brief acceleration that produced an intense spark for starting. After engine start, the impulse coupling would disengage and return the magneto to normal engine timing.

The airplane Pilot’s Operating Handbook and FAA-Approved Airplane Flight Manual checklists for loss of engine power in-flight and engine-driven fuel pump failure both instructed the pilot to turn on the electric fuel pump.

Based on pilot logbook information and ADS-B data, the airplane had been operated about 113 hours since the airplane’s last annual inspection. WRECKAGE AND IMPACT INFORMATIONExamination of the accident site revealed the airplane impacted heavily wooded, mountainous terrain about 11 nm east-northeast from 20A, the airport to which the pilot was vectored. A postimpact fire started a forest fire, which burned several acres. Small fires remained burning among the wreckage throughout the on-site examination.

Further examination of the accident site revealed impact-damaged trees at decreasing heights of about a 10° slope from the first impacted tree to the resting position of the main wreckage about 220 ft away. The damage to the trees was consistent with the airplane being in a wings-level attitude on an energy path of about 190° magnetic.

Examination of the wreckage revealed the cockpit, cabin, empennage up to about 60 inches forward of the leading edge of the stabilator, and both wings were extensively damaged by postimpact fire. Both wing leading edges displayed damage consistent with tree strikes. The engine, which remained attached to the firewall by the engine mount, was upright, and the attached propeller sustained significant postimpact fire damage. No identifiable instruments, gauges, or switches were located in the cockpit.

The airframe fuel system was largely destroyed by impact forces and postimpact fire. The fuel selector valve was heavily fire damaged; although it was found in the right tank position, its preimpact position could not be determined because portions of it were missing and it was free to move. The electric fuel pump was not located.

Examination of the flight controls for roll, pitch, and yaw revealed no evidence of preimpact failure or malfunction. The stabilator trim actuator had one inch of threaded rod extension on the top of the drum, which equated to a slight nose-up trim setting. The electrically-driven flap actuator was found in the flaps 40° extended position.

Examination of the engine revealed no evidence of preimpact failure or malfunction of the crankshaft, camshaft, valvetrain, air induction, exhaust, lubrication, turbocharger, or fuel metering systems. Following removal of the heat-damaged left magneto, which could not be operationally tested, the left gear retainer assembly (part number [P/N] LW19096) was observed to be fractured, and the drive cushions were damaged, sections of which were found in the oil sump along with ferrous parts. Additionally, the left crankshaft idler gear assembly (P/N 71668) and the fuel pump idler gear assembly (P/N 71664) exhibited damaged and missing teeth.

The right magneto was heat damaged and the right gear retainer assembly (P/N LW19096) was in place and intact with one drive cushion intact and the other drive cushion fractured. The fractured left gear retainer assembly, gears with fractured teeth, ferrous components found in the oil sump, including fractured sections of a pawl retaining rivet, and the heat-damaged left magneto were retained for examination by the NTSB Materials Laboratory.

Upon partial disassembly of the left magneto, both pawl retaining rivets were found to be fractured; remnants of each rivet remained loosely entrapped by the pawls. Both pawl retaining rivets exhibited indications of wear on the shafts, consistent with deformation on the respective holes of the impulse hub assembly. One of the rivet pieces found in the oil sump exhibited features consistent with fatigue cracking that had initiated at multiple locations along an area of wear. The other rivet fracture feature was consistent with torsional and shear overstress. Further examination of the left magneto revealed that the impulse shell was cracked and there was an outward tear in part of the skirt or side flange. Additionally, a wear mark with smearing and an impact mark consistent with contact by the magneto stop pin was noted, although there was no flattening of the stop pin. The fracture features of all fractured teeth and the left gear retainer assembly were consistent with overstress fracture with no indication of preimpact failure or malfunction.

Examination of the propeller revealed all three blades remained secured inside the propeller hub and exhibited blade bending with no evidence of propeller preimpact failure or malfunction. ADDITIONAL INFORMATION14 CFR 91.3 (Responsibility and authority of the pilot in command) states, “in an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of [14 CFR 91] to the extent required to meet that emergency.”

Section 3-3-2 (CLOSED/UNSAFE RUNWAY INFORMATION) of FAA Order JO 7110.65AA (Air Traffic Control) states:
If an aircraft requests to takeoff, land, or touch-and-go on a closed or unsafe runway, inform the pilot the runway is closed or unsafe, and
a. If the pilot persists in his/her request, quote him/her the appropriate parts of the NOTAM applying to the runway and inform him/her that a clearance cannot be issued.
b. Then, if the pilot insists and in your opinion the intended operation would not adversely affect other traffic, inform him/her that the operation will be at his/her own risk.
PHRASEOLOGY
RUNWAY (runway number) CLOSED/UNSAFE. If appropriate, (quote NOTAM information), UNABLE TO ISSUE DEPARTURE/LANDING/TOUCH-AND-GO CLEARANCE. DEPARTURE/LANDING/TOUCH-AND-GO WILL BE AT YOUR OWN RISK. MEDICAL AND PATHOLOGICAL INFORMATIONAn autopsy of the pilot was performed by the Alabama Department of Forensic Sciences, Huntsville, Alabama. According to the autopsy report, the cause of death was probable blunt force injuries complicated by thermal injuries, and the manner of death was accident.

Toxicology testing performed by the FAA Forensic Sciences Laboratory on the pilot’s specimens identified no evidence of impairing drugs.

About This NTSB Record

This aviation event was investigated by the National Transportation Safety Board (NTSB). NTSB investigates all U.S. civil aviation accidents to determine probable cause and issue safety recommendations to prevent future accidents.

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