Hollywood, FL, USA
N3UH
LANCAIR LEGACY FG
The pilot was departing in the experimental, amateur-built airplane from his home airport. Data retrieved from an onboard electronic flight instrument indicated that, shortly after takeoff the engine lost partial power. While attempting to turn back to the airport, the pilot exceeded the airplane’s critical angle of attack and the airplane entered an aerodynamic stall and rolled to the right, impacting terrain in a nose- and right-wing-down attitude. Further examination of the data indicated that, when the partial loss of power occurred, the exhaust gas temperature for cylinder No. 1 showed a marked divergence from the other cylinders and the engine speed dropped to 1,600 rpm with manifold pressure decreasing to about 12 inHg. A few seconds later, the manifold pressure had increased to about 22 inHg and engine speed had increased to about 2,300 rpm, consistent with the other three cylinders continuing to function, and also consistent with the engine responding to pilot inputs. The data also indicated that at this time, the pilot allowed the airplane to pitch up, and the airplane reached its critical angle of attack; a right roll of over 100° developed before the airplane impacted the ground. No preimpact failures or malfunctions of the airplane or engine were discovered that would have precluded normal operation, with the exception of the No. 1 cylinder’s top sparkplug and adapter, which had blown out of the top sparkplug hole in the No. 1 cylinder. The sparkplug was still attached to its high-tension lead, and was still threaded into its adapter, but displayed thread damage on the two lower threads of the adapter, with no evidence of an anti-seize compound being applied to the threads. This was likely indicative of improper installation, either by application of inadequate torque or cross-threading during installation. The airplane’s maintenance logbooks were not located and it could not be determined whether the airplane had a current condition inspection at the time of the accident. The mechanic who performed the airplane’s most recent condition inspection reported that he had observed the pilot maintain the accident airplane on a number of occasions, most recently within the month that the accident occurred. The mechanic reported that at that time, he saw the airplane “opened up,” with numerous sticky notes on various parts of the engine. The pilot kept an air compressor and differential compression tester in his hangar, which suggested that the pilot was familiar with removing the sparkplugs and adapters and how to perform a compression test. Additionally, a notebook the pilot kept contained a partial date that was likely entered about 3 days before the accident, which appeared to be cylinder pressure readings for each cylinder. It is possible that the pilot may have performed a compression test on the engine in anticipation of it being accepted by a mechanic as part of an owner-assisted inspection and that he improperly reinstalled the No. 1 cylinder top sparkplug adapter following that compression test. Based on the available information, it is likely that the pilot experienced a partial loss of engine power after takeoff when the No. 1 cylinder top sparkplug separated from the cylinder as a result of improper installation. During the pilot’s attempt to return to the airport, he exceeded the airplane’s critical angle of attack and the airplane entered an aerodynamic stall.
HISTORY OF FLIGHTOn 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 pilot was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The airplane was based at North Perry Airport (HWO), Hollywood, Florida, and was departing from that airport when the accident occurred. The pilot was cleared for takeoff from runway 1L at taxiway M and was instructed to make a left turn westbound after departure. Track data recovered from an onboard electronic flight instrument indicated that the airplane departed runway 1L, and about 0.5 miles from the departure end of the runway, the pilot reported that the airplane’s engine was running rough, and he requested to return to the airport to land. The airplane then 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 subsequently impacted the ground about 200 ft before runway 28R. According to witnesses, just prior to impact, the airplane was nearly parallel to the extended centerline of runway 28R in a 45° nose-down attitude. Review of data retrieved from the onboard electronic flight instrument indicated that, around 1522:25, about 25 seconds after takeoff, the airplane’s airspeed reached a maximum of around 92 knots, and altitude was increasing. Cylinder head temperatures and exhaust gas temperatures were nominal for the first portion of the flight immediately following takeoff and through a portion of the airplane’s climb. As altitude continued to increase, airspeed and groundspeed began to decrease. Around 1522:35, the airplane began a right turn, and altitude continued to increase until approximately 1522:40, when the altitude stabilized around 246 feet msl. It is possible that at this time the altitude data was unreliable, given the repeated nature of the sampled data at 246 feet msl until approximately 1523:05, when a decreasing altitude trend began. Also around this time, the exhaust gas temperature in cylinder No.1 showed a marked divergence from the other cylinders and engine speed dropped to around 1,600 rpm with manifold pressure decreasing to about 12 inHg. As the altitude data stabilized, indicated airspeed data also stabilized while groundspeed increased. The approximate difference between airspeed and groundspeed at this time was around 13 knots, with the recorded groundspeed being higher than the recorded indicated airspeed data. By 1523:05, altitude data began decreasing as recorded angle of attack and pitch values began increasing. At 1523:09, manifold pressure increased to around 22 inHg and engine speed increased to about 2,300 rpm. At this time, the data also showed the airplane’s pitch increased along with its angle of attack. The angle of attack value reached 100% (critical angle of attack) about 1523:10. The last two data points showed values for pitch decreasing rapidly and a right roll of over 100°. The recorded data ended at 1523:12. AIRCRAFT INFORMATIONDuring the investigation, no maintenance logbooks were discovered or provided to the NTSB. Nor was any evidence of a recent condition inspection discovered. A family member, however, did provide photos of maintenance records that had been sent by the pilot to a prospective buyer of the airplane. The photos indicated that a condition inspection was completed on November 10, 2019. According to a family member, a buyer was scheduled to fly from Texas to Florida to see the airplane the same week that the accident happened. The buyer mentioned to him that the airplane was supposed to have a fresh inspection and he believed that the pilot may have found a new mechanic, and that person may have the maintenance logbooks in their possession. He also advised that, in the past, the pilot had participated in owner-assisted inspections and was unaware of any engine problems with the airplane. The mechanic who completed the November 10, 2019, condition inspection, reported that he had not performed an inspection of the airplane in 2020. He mentioned that the pilot had requested he perform the condition inspection for the year 2020; however, he was unable to do so due to prior commitments. The mechanic also advised that, due to the close proximity of their hangars at HWO, it was not uncommon for the pilot to come by his hangar and borrow tools and/or seek his advice on matters concerning his airplane. The mechanic observed the pilot maintain his own airplane on a number of occasions, the last time being earlier the month of the accident. The mechanic recalled seeing the panel mounted avionics disassembled, and "sticky notes" placed on numerous parts of the engine. He stated that not only were the avionics all removed, but the airplane was opened up, as if someone was performing a condition inspection. He added that he was unaware of any other mechanic that may have worked on the airplane and was unaware of the whereabouts of the maintenance logs. On December 23, 2020, it was discovered that the pilot kept an air compressor and differential compression tester in his hangar. A differential compression tester is used to determine the amount of leakage past piston rings and valves in an engine cylinder and requires the removal of one of the sparkplugs and adapters in the cylinder to connect the tester, and replacement of the sparkplug and adapters after the testing was complete. A review of photographs taken by the FAA also revealed that a notebook the pilot kept, contained a page with the mechanic’s name on it, the word “Inspection” and a date of “11-10-20.” The last page of the notebook also contained an entry which had a partial date of “11-20- “, numbers that corresponded to the cylinders on the engine, and what appeared to be cylinder pressure readings for each cylinder. AIRPORT INFORMATIONDuring the investigation, no maintenance logbooks were discovered or provided to the NTSB. Nor was any evidence of a recent condition inspection discovered. A family member, however, did provide photos of maintenance records that had been sent by the pilot to a prospective buyer of the airplane. The photos indicated that a condition inspection was completed on November 10, 2019. According to a family member, a buyer was scheduled to fly from Texas to Florida to see the airplane the same week that the accident happened. The buyer mentioned to him that the airplane was supposed to have a fresh inspection and he believed that the pilot may have found a new mechanic, and that person may have the maintenance logbooks in their possession. He also advised that, in the past, the pilot had participated in owner-assisted inspections and was unaware of any engine problems with the airplane. The mechanic who completed the November 10, 2019, condition inspection, reported that he had not performed an inspection of the airplane in 2020. He mentioned that the pilot had requested he perform the condition inspection for the year 2020; however, he was unable to do so due to prior commitments. The mechanic also advised that, due to the close proximity of their hangars at HWO, it was not uncommon for the pilot to come by his hangar and borrow tools and/or seek his advice on matters concerning his airplane. The mechanic observed the pilot maintain his own airplane on a number of occasions, the last time being earlier the month of the accident. The mechanic recalled seeing the panel mounted avionics disassembled, and "sticky notes" placed on numerous parts of the engine. He stated that not only were the avionics all removed, but the airplane was opened up, as if someone was performing a condition inspection. He added that he was unaware of any other mechanic that may have worked on the airplane and was unaware of the whereabouts of the maintenance logs. On December 23, 2020, it was discovered that the pilot kept an air compressor and differential compression tester in his hangar. A differential compression tester is used to determine the amount of leakage past piston rings and valves in an engine cylinder and requires the removal of one of the sparkplugs and adapters in the cylinder to connect the tester, and replacement of the sparkplug and adapters after the testing was complete. A review of photographs taken by the FAA also revealed that a notebook the pilot kept, contained a page with the mechanic’s name on it, the word “Inspection” and a date of “11-10-20.” The last page of the notebook also contained an entry which had a partial date of “11-20- “, numbers that corresponded to the cylinders on the engine, and what appeared to be cylinder pressure readings for each cylinder. WRECKAGE AND IMPACT INFORMATIONExamination of the wreckage revealed damage consistent with the airplane impacting in a nose- and right-wing-low attitude. The nose section, canopy, and both wings separated during the impact sequence. The aft fuselage and empennage remained intact. Flight control continuity was established from the ailerons, elevators, and rudder through breaks in the flight control system to the cockpit controls. The pitot tube was clear of obstructions. Both wing fuel tanks were breached and void of fuel. The electric fuel pump was ON. The fuel selector valve was in the RIGHT tank position; it moved freely and did not contain any blockages. Two of the three composite propeller blades were separated at the blade root, and the third blade was separated about 12 inches outboard of the blade root. Examination of the engine revealed that fuel was present in the fuel manifold and fuel servo. The electronic ignition system for the top sparkplugs was impact damaged and non-functional. The magneto for the bottom sparkplugs did not produce spark. Internal examination of the magneto revealed that the points had been impact damaged but there was no evidence of any preimpact failures or malfunctions of the magneto. The automotive style spark plugs and spark plug adapters were secure in their respective engine cylinders 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 sparkplug was still attached to its high-tension lead and threaded into its adapter, but displayed thread damage on the two lower threads of the adapter and was missing its copper washer. Thumb compression and suction was attained on all cylinders, oil was present in the rocker boxes and oil sump, and drivetrain continuity was established throughout the engine. Review of the electronic ignition system’s written installation guidance indicated that the spark plug adapters were supposed to be installed in the cylinder head using a supplied copper washer and then torqued to 35 to 45 ft-lbs. using an anti-seize compound. The automotive style spark plugs were supposed to be installed with their washer and torqued to 20 ft-lbs. using an anti-seize compound. Further examination of the adapters did not reveal the presence of any anti-seize on the threads, and the damage to the last two threads on the adapter for the No. 1 cylinder top sparkplug was indicative of inadequate torque or cross threading during installation, and the plug being blown out of the cylinder.
The pilot/owner’s failure to properly reinstall the number 1 cylinder spark plug, which resulted in a partial loss of engine power during the initial climb. Contributing was the pilot's exceedance of the airplane’s critical angle of attack during an attempted return to the airport following the partial loss of engine power, which resulted in an aerodynamic stall, loss of control, and impact with terrain.
Source: NTSB Aviation Accident Database
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