Accident Overview
On August 23, 2014, at approximately 1210 eastern daylight time, a Piper PA-28-180, registration N9095J, operated by Old Cherokee LLC, was substantially damaged during a forced landing at Montgomery County Airpark (GAI) in Gaithersburg, Maryland. The commercial-rated pilot, the sole occupant, sustained serious injuries. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed for the flight to Essex County Airport, Caldwell, New Jersey. The flight was originating at the time of the accident.
Pilot Narrative
The pilot reported performing a preflight inspection using a laminated Piper checklist, step by step. He then had the left fuel tank fueled, which he observed. About 20 to 25 minutes after fueling, he checked both fuel tank sump drains and the fuel strainer for contaminants; none were found. He started the engine, obtained an IFR clearance, and taxied to the run-up area for runway 14. During the run-up, he performed systems checks using the checklist and noted everything was normal, including magneto drops within normal range. He obtained his IFR departure clearance and taxied onto the runway. Aware of the new engine, he applied partial power, released the brakes, then added full power with the fuel selector positioned to the right tank. The tachometer indicated approximately 2,475 to 2,500 rpm, and the airplane accelerated normally with all instruments in the green. He allowed the airplane to fly off the runway, noting the takeoff roll seemed normal.
After becoming airborne, while climbing at Vy speed at about 100 feet above ground level, the engine surged once. The pilot described the surge as similar to a leaned fuel-to-air ratio before shutdown. He leveled off, and the engine operated normally without further surging. He allowed the airplane to accelerate to good forward speed, then relaxed forward pressure to climb. During a climb about 100 feet higher, the engine suddenly failed or quit. With trees, houses, and a road ahead, he decided an on-airport landing was best. He attempted troubleshooting by switching fuel tanks, but engine power did not restore. He announced the engine failure on the radio and turned left toward an area north of the runway. At some point, he turned off the fuel selector. He did not believe the propeller stopped. He bled off airspeed and impacted the ground with the left wing first, followed by the left main landing gear. He believed he was in controlled flight and had not stalled the airplane.
Witness Accounts
Two witnesses were interviewed by an NTSB National Resource Specialist (Aviation Systems Engineer) at GAI hours after the accident. One witness, located at a hangar at the departure end of runway 14, reported hearing the engine hesitate, then pick up again, then sputter and quit. He observed the airplane bank left and impact left wing low. The other witness, in an airplane, reported the accident airplane flew over him at 100 feet, then the engine went to idle. He noticed the left wing drop and the airplane descend in a steep constant spiral to the ground. He secured his airplane and ran to the accident site to render assistance.
Wreckage Examination
According to the NTSB National Resource Specialist (Aviation Systems Engineer) who inspected the wreckage, the airplane was heading 220 degrees magnetic, roughly perpendicular to runway 14. The wreckage location was to the left of the departure end of the runway, bounded by final taxiways and a run-up area. The left wingtip was found 63 feet forward of the engine’s resting position, 23 feet from a heavy ground scar of fuselage width. Clear plastic window material was near this scar. The magnetic heading from the wingtip to the front of the engine was 100 degrees.
The main landing gear remained attached to each wing; the nose landing gear was separated and lay between the nose and the ground scar. The right wingtip was oriented upward, with the wing attached to the fuselage. The left wing was inverted and only connected by control cables. Witnesses reported moving the wing to help extricate the pilot. The baggage door was open, revealing one or two large black fabric suitcases.
Substantial fuel was found in both wing fuel tanks, and a heavy fuel smell was present. The propeller was found at the 2 to 8 o’clock orientation. One blade was bent back beneath the engine cylinders; the leading edges of both blades were not damaged. Impact damage was noted near the gascolator, which had a loose metal bowl and fuel drain containing small amounts of dirt and paint chips.
Engine and Fuel System Inspection
In the cockpit, the fuel selector was found at the 9 o’clock position (left tank). Witnesses reported turning off switches that appeared to be in the ON position; all switches were initially found OFF. Both cockpit yokes were bent downward, and the flap handle was in the UP position. Approximately 26.5 gallons of fuel were drained from the airplane. The right wing was 3/4 full, and the left wing, nearly inverted and sheared off, contained 10 gallons. No fuel contamination was noted. The ELT had activated; the boost pump, still operating, was turned off. The battery was disconnected due to impact damage to the master switch. The stall warning light bulb showed no filament stretching.
Inspection by a representative of the engine manufacturer, with oversight from an FAA inspector or an IA mechanic, revealed as-found cockpit positions: carburetor heat OFF, throttle full forward, mixture idle cut-off, fuel selector OFF, tachometer reading 3003.74. The pilot’s shoulder harness remained attached, the seat was broken loose, and floorboards were displaced. An Insight G2 Graphic Engine monitor with a 2 GB SD card was installed; the card was later read by the NTSB Vehicle Recorder Laboratory.
Engine inspection showed the throttle, mixture, and carburetor heat controls were connected. The carburetor heat control on the airbox and the mixture and throttle levers matched cockpit positions. The crankshaft was slightly bent and cracked at the nose seal, precluding an engine run. Crankshaft, camshaft, and valve train continuity was confirmed via hand rotation. Thumb compression and valve train continuity were noted in all cylinders. Both magnetos operated during hand rotation; magneto-to-engine timing could not be determined due to a broken starter ring gear, but they were timed between 25 and 30 degrees BTDC (specification 25 degrees). The air induction system was unobstructed, and the bracket air filter appeared freshly oiled. The engine-driven fuel pump operated satisfactorily by hand; residual fuel consistent with 100 low lead was found in the pump and lines.
The AVSTAR carburetor had a clean inlet screen. Disassembly revealed about 5 ounces of fuel in the bowl; metal floats were not crushed. No water was detected using water finding paste. The accelerator pump and needle valve/seat functioned properly during hand movement. The carburetor was retained for further inspection at the manufacturer’s facility. Magnetos sparked at all ignition leads when spun. Spark plugs showed normal wear and color per Champion Aviation Check-A-Plug chart. No rich or lean indications were found. The ignition key was not found, so a switch check could not be performed.
The gascolator bowl was broken, the screen clean, and the housing broken at the inlet. No blockage was found in fuel supply lines from the firewall to the carburetor inlet. The fuel selector was in the OFF detent; impact damage precluded full rotation. Detents for left and right positions were felt. Air blown through the left tank supply line passed to the fuel strainer with no obstructions; no air was felt at the right fuselage root. Similarly, the right tank supply line was clear. The off position blocked airflow. Fuel supply and vent lines in both wings were unobstructed.
The two-bladed fixed-pitch propeller had one blade bent aft about 20 degrees starting 8 inches from the hub, with chordwise scratches on the cambered side; the other blade was undamaged and unscratched.
Data Analysis
Maintenance records indicated the engine was factory overhauled and shipped in November 2013, installed in the accident airplane in March 2014, and had accrued about 30 hours since overhaul at the time of the accident.
Data from the Insight G2 Graphic Engine monitor recorded the accident flight. Parameters included carburetor temperature, buss voltage, cylinder head temperature (CHT), exhaust gas temperature (EGT) for all cylinders, outside air temperature, and fuel flow. The data showed a rapid decrease in fuel flow from about 10 GPH to 4 GPH, with a corresponding decrease in EGT for all cylinders. Fuel flow then sharply increased to about 6 GPH, with a corresponding increase in EGT, then again sharply decreased to about 4 GPH with a corresponding EGT drop.
According to the airplane type certificate data sheet, maximum permissible takeoff rpm is 2,475, and for all other operations, 2,700 rpm.
Carburetor inspection at the manufacturer’s facility revealed the float height was slightly less than specification during physical inspection but within limits during bench testing. The unit passed all test points on a test bench with airflow. After testing, the needle seat was found slightly less than specification.
A surface aviation observation report at GAI at 1215, about 5 minutes after the accident, recorded temperature 20°C (68°F) and dew point 18°C (64°F). A review of FAA Special Airworthiness Information Bulletin (SAIB) on carburetor ice prevention indicates that these conditions were favorable for serious icing at glide power.