History of Flight
On November 23, 2020, about 1523 eastern standard time, an experimental, amateur-built Lancair Legacy FG airplane, N3UH, was substantially damaged when it was involved in an accident near Hollywood, Florida. The airplane was based at North Perry Airport (HWO) and departed from runway 1L. The pilot was cleared for takeoff with instructions to make a left turn westbound after departure. Track data from an onboard electronic flight instrument indicated that the airplane departed runway 1L. About 0.5 miles from the departure end, the pilot reported the engine running rough and requested to return for landing. The airplane made a right turn toward the airport, and the controller cleared the pilot to land on any runway. The pilot requested and was cleared to land on runway 28R. The airplane impacted the ground about 200 feet before runway 28R. Witnesses observed the airplane nearly parallel to the extended centerline of runway 28R in a 45° nose-down attitude.
Review of the onboard electronic flight instrument data showed that around 1522:25, about 25 seconds after takeoff, airspeed reached a maximum of about 92 knots and altitude was increasing. Cylinder head temperatures and exhaust gas temperatures were nominal. As altitude increased, airspeed and groundspeed began to decrease. Around 1522:35, the airplane began a right turn, and altitude increased until approximately 1522:40, when it stabilized around 246 feet msl. It is possible that the altitude data was unreliable at that point. At that time, the exhaust gas temperature in cylinder No.1 showed a marked divergence from the other cylinders, engine speed dropped to around 1,600 rpm, and manifold pressure decreased to about 12 inHg. As altitude data stabilized, indicated airspeed stabilized while groundspeed increased. By 1523:05, altitude data began decreasing, and recorded angle of attack and pitch values increased. At 1523:09, manifold pressure increased to about 22 inHg and engine speed to about 2,300 rpm. The pitch and angle of attack increased further, and the angle of attack reached 100% (critical) about 1523:10. The last two data points showed pitch decreasing rapidly and a right roll of over 100°. The data ended at 1523:12.
Aircraft and Maintenance Information
During the investigation, no maintenance logbooks were discovered. A family member provided photos of maintenance records indicating a condition inspection was completed on November 10, 2019. A buyer was scheduled to see the airplane the same week of the accident, and the buyer believed the airplane was supposed to have a fresh inspection. The mechanic who performed the November 2019 inspection reported he had not done an inspection in 2020. The mechanism observed the pilot maintaining his own airplane, and earlier in the month of the accident, the mechanic saw the panel avionics disassembled and sticky notes on the engine, as if a condition inspection was being performed. On December 23, 2020, an air compressor and differential compression tester were found in the pilot's hangar. A notebook contained a page with the mechanic's name, the word "Inspection," and a date of "11-10-20," and another page with cylinder numbers and what appeared to be pressure readings.
Wreckage Examination
Examination of the wreckage revealed damage consistent with a nose- and right-wing-low impact attitude. The nose section, canopy, and both wings separated. Flight control continuity was established. The pitot tube was clear. Both wing fuel tanks were breached and void of fuel. The electric fuel pump was ON, and the fuel selector valve was in the RIGHT tank position. Two of three composite propeller blades separated at the blade root, and the third separated about 12 inches outboard.
The engine examination showed fuel present in the fuel manifold and servo. The electronic ignition system was impact damaged. The magneto for the bottom spark plugs did not produce spark due to impact damage, with no evidence of preimpact failure. The automotive-style spark plugs and adapters were secure except for the top spark plug and adapter on the No.1 cylinder, which was not in its hole. The No.1 cylinder's top spark plug was still attached to its high-tension lead and threaded into its adapter, but the adapter displayed thread damage on the two lower threads and was missing its copper washer. Thumb compression and suction were attained on all cylinders, oil was present, and drivetrain continuity was established. The electronic ignition installation guidance specified that the spark plug adapters be installed with a copper washer and torqued to 35 to 45 ft-lbs using anti-seize compound; automotive spark plugs required 20 ft-lbs. No anti-seize was found on the adapter threads, and the thread damage indicated inadequate torque or cross-threading during installation, leading to the plug being blown out of the cylinder.