History of Flight
On October 21, 2022, about 1845 eastern daylight time, a Beech A24R, registration N8020R, was destroyed when it collided with a storage building attached to an apartment building near Keene, New Hampshire. The flight instructor and commercial-rated pilot on board were fatally injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Audio recordings from the common traffic advisory frequency at Dillant/Hopkins Airport (EEN) indicated that at about 1842, one pilot broadcast the airplane was taking runway 02 for departure. Approximately two minutes later, a pilot announced departure from runway 02 and intent to remain in the traffic pattern.
Video from the airport showed the airplane began its takeoff from the approach end of runway 02. Multiple witnesses on the airport, including pilots and a mechanic, reported the engine sounded abnormal; one said it never sounded smooth during the takeoff or while airborne. The airplane rotated about 3,311 feet down the 6,201-foot runway and climbed to about 25 feet above ground level. A pilot-rated mechanic heard a momentary power reduction followed by a power advance when airborne over the runway.
After takeoff, witnesses observed a very shallow climb, reaching between 50 and 200 feet near the intersection of runways 02/20 and 14/32, about 5,200 feet down the runway. The flight maintained a wing- and nose-level attitude while the poor engine sound continued. A witness about 0.5 nautical mile north-northeast of the departure end reported the airplane passed at about 50 feet above ground level, emitting rapid "pop pop pop" sounds resembling backfiring. The airplane cleared a neighbor's house and a tree line, after which the popping ceased, then resumed after three seconds. The engine sound grew louder as the airplane descended. The witness heard the impact and proceeded to the site. No distress call was made on the CTAF.
The airplane struck a storage building attached to an apartment building, resulting in a postcrash fire. No ground injuries were reported.
Aircraft Information
The airplane was equipped with a three-bladed, constant-speed McCauley propeller installed per Supplemental Type Certificate SA496CH. The FAA-approved Airplane Flight Manual Supplement specified no performance change from the original propeller and a rated full power rpm of 2,700. The Pilot's Operating Handbook and FAA-approved Airplane Flight Manual (POH/AFM) stated the static rpm range during a power check should be 2,650 to 2,700 rpm. Performance data indicated a ground roll of about 1,224 feet at 2,750 pounds on a paved, level, dry runway, with an 8% reduction per 100 pounds below that weight.
The accident airplane had not been flown since September 4, 2021, over 13 months before the accident. The pilot occupying the left seat during that flight reported two flights in the airplane: 1.3 hours on August 28, 2021, and 1.2 hours on September 4, 2021. The airplane performed normally on the first flight and the first two legs of the second flight, but during the third leg, the engine sounded like a fouled spark plug or bad magneto during taxi. The airplane did not accelerate as expected on takeoff; the right-seat pilot (the accident flight instructor) aborted the takeoff. After another run-up and magneto check, a second takeoff was attempted. The airplane did not become airborne until 2,200 to 2,500 feet down the runway, climbed at about 100 feet per minute, and nearly struck a tree. The right-seat pilot made zigzag turns up a valley until clearing a ridgeline and landing uneventfully at EEN. The left-seat pilot described it as the "worst flight of my life."
The owner/operator stated the airplane had been hangared since the September 2021 event. She and a mechanic indicated the issue was a plugged fuel injector.
The last annual inspection was completed on October 19, 2022. During the inspection, fuel injector nozzles were cleaned, five spark plugs replaced, and magnetos retimed. All differential compression checks exceeded 75 psi at 80 psi. A full-power post-maintenance engine run earlier on the accident day achieved a maximum rpm between 2,300 and 2,375. No post-maintenance check flight was performed; the accident flight was the first flight after the annual inspection.
Lycoming Service Bulletin No. 1414B and Service Instruction No. 1275C provide instructions for cleaning, removing, cleaning, reassembling, and testing of fuel injector nozzles.
Wreckage and Impact
The accident site was approximately 0.54 nautical mile north-northeast of the departure end of runway 02. Examination showed extensive heat and impact damage to the storage building, its contents, several apartments, and the roof. The displaced metal roof of the storage shed bore red paint transfer oriented on a magnetic heading of 021°, located to the right of the energy path. Two parallel slash marks 66 inches apart were found on the roof, not oriented consistently with the flight direction. The aft portion of the empennage, heat-damaged left wing sections, pitot tube, and melted aluminum were atop the roof. Additional debris was scattered among the building remains. The engine with attached propeller was resting on its right side forward of the aft empennage. No bird remains were found.
The cockpit, cabin, right wing, part of the left wing, and forward empennage were largely consumed by postcrash fire to approximately fuselage station 250.00. One restraint buckle was found in the buckled position and released easily. Several flight instrument remains were recovered, but readings could not be determined.
Flight control cables for pitch and yaw showed no preimpact failure or malfunction. Separated direct aileron control cables had cuts consistent with first responder actions and thermal damage; NTSB Materials Laboratory analysis indicated the fracture profile was consistent with tensile overstress. The stabilator trim measurement was 0.875 inch, correlating to near neutral. The flap actuator was not located.
The airframe fuel supply and vent systems sustained extensive heat damage; the fuel selector valve was not located.
The engine, heavily fire-damaged, exhibited crankshaft, camshaft, and valvetrain continuity. Thumb suction and compression were noted at each cylinder. Borescope inspection revealed no discrepancies. There was no evidence of preimpact failure or malfunction of ignition, air induction, exhaust, lubrication systems, engine-driven fuel pump, flow divider, fuel servo, or fuel injector lines. A slight amount of water was expelled from the No. 4 fuel injector line during examination; its source was not tested due to the circumstances and firefighting efforts.
Visual examination of each two-piece fuel injector nozzle showed a clean/soot demarcation line along the thread ends where the fuel injector line attached. None had an insert or restrictor installed. Flow testing as received could not be completed due to excessive bleed hole leakage, which stopped after an exemplar insert was installed. With exemplar inserts installed, a soot/clean demarcation line was observed on threads between about 0.026 and 0.044 inch below the lower edge of the union nut. Tightening the line to 50 inch-pounds changed the nut dimension by about 0.0008 inch.
Testing of a four-cylinder engine from the same manufacturer with all inserts/restrictors installed produced 162.68 corrected horsepower; with all removed, 152.07; with one removed, 128.10. Without inserts, fuel leakage was noted at the nozzles onto the air induction tubes.
The heat-damaged propeller blades were free to rotate in the hub, with retaining rings dislodged. The blade angle at impact could not be determined, but internal impact marks indicated it was at or near the low pitch stop. No preimpact failure or malfunction was found.
The propeller governor, attached to the accessory housing and heat-damaged, was examined at the manufacturer's facility. With exemplar parts installed, operational testing revealed minor out-of-tolerance values but no preimpact failure or malfunction that would have precluded normal operation.
Additional Examinations
NTSB analysis of video containing sound indicated engine rpm was at or near 2,400 rpm during departure and just before impact. About 16 seconds after lift-off, one camera recorded sounds similar to engine popping lasting about 2 seconds.
Medical and Pathological Findings
Postmortem examinations by the New Hampshire Medical Examiner's Office determined the cause of death for both pilots was inhalation of smoke and toxic products of combustion. Forensic toxicology by the FAA Forensic Sciences Laboratory revealed the flight instructor had 14% carboxyhemoglobin and 1.09 µg/mL cyanide in heart blood; the commercial-rated pilot had 47% carboxyhemoglobin and 1.05 µg/mL cyanide.