History of Flight
On April 23, 2012, at 1017 Pacific daylight time, an experimental League Lancair IV-TP, registration N66HL, departed controlled flight and broke up in flight 5 nautical miles southeast of Sisters, Oregon. The private pilot and his certified flight instructor (CFI) sustained fatal injuries, and the airplane, which was owned and operated by the pilot, sustained substantial damage. The local 14 Code of Federal Regulations Part 91 instructional flight departed Roberts Field, Redmond, Oregon, about 0950, and was conducted in visual meteorological conditions. No flight plan was filed.
The purpose of the flight was for the CFI to conduct a flight review of the private pilot in his high-performance, experimental, amateur-built airplane. Flight track data recorded from the airplane's global positioning system (GPS) was extracted from the onboard Chelton multi-functional display (MFD) compact flash memory card recovered from the wreckage. The flight data file started at 0948:34 and captured data at 1-second intervals.
The data spanned 28 minutes and 46 seconds. It showed the airplane departing Roberts Field from runway 10, then reversing course and climbing to about 10,500 feet mean sea level (msl). Starting about 1008:30, the airplane made several shallow banks before beginning a 7-nautical-mile southwest stretch at 10,500 ft msl.
At 1015:20, the airplane was at 10,455 ft msl and began a right turn, completing a 360-degree circle about 2.8 nm in diameter over about 1 minute 30 seconds. During the turn, it initially descended to about 10,250 ft msl then climbed to about 11,600 ft msl. The airplane then reached its highest altitude of about 11,720 ft msl at 1016:47 before descending as the turn tightened into a hook shape. Over 15 seconds, altitude decreased over 3,900 ft to 6,445 ft at the last recorded data point at 1017:13.
Starting at about 1016:40, the pitch angle dropped from 9 degrees nose-up to 68 degrees nose-down, vertical speed decreased from a 2,000 feet per minute (fpm) climb to a 22,000 fpm descent, g-load increased to 7 gs, and indicated airspeed increased to about 310 knots.
Personnel Information
The CFI, age 52, held a CFI and airline transport pilot certificate with ratings for single-engine and multi-engine land and instrument flight. His most recent second-class medical certificate was issued on February 22, 2012. He had a history of severe obstructive sleep apnea treated with a CPAP device. His total flight experience was 11,098.4 hours, with 5,320.2 hours in turbine-engine airplanes. He had flown the accident airplane about 18 hours, all as a CFI. His weight was estimated at 220 pounds.
The pilot-owner, age 68, held a private pilot certificate with single-engine land, complex, and instrument ratings. His most recent second-class medical certificate was issued as limited on May 5, 1997. He held a repairman experimental aircraft builder certificate and built the airplane. He did not hold a current medical due to health issues and always flew with CFIs approved on his insurance. His logbooks showed about 785 total hours, of which 217 were in high-performance turbine airplanes. His weight was estimated at 210 pounds.
Aircraft Information
The Lancair IV-TP is an amateur-built experimental airplane of composite materials, with four seats, retractable tricycle landing gear, and traditional flight controls. It received a special airworthiness certificate in October 2008. The airplane was equipped with a Walter/General Electric M601E-11A engine rated at 751 shaft horsepower and a three-bladed Avia propeller. Test flights were completed in September 2009. The airplane's estimated stalling speed in landing configuration (Vso) at a weight of 3,750 lbs was 61 knots.
Maintenance records showed the airplane had accumulated about 463 total hours at the last recorded maintenance on April 4, 2012. Based on Chelton data, total fuel at startup was 138 gallons; at the last data point it was 119 gallons.
Weight and balance was estimated: gross takeoff weight (GTOW) 3,934.4 lbs, center of gravity 138.5 inches aft of datum. The weight at the time of the accident was estimated at 3,628 lbs. The airplane's weight and balance record indicated maximum GTOW of 3,800 lbs and CG range of 132 to 144 inches. Lancair-recommended maximum GTOW for the IV-TP with turboprop engine and winglets was 3,550 lbs.
Performance Study
An NTSB engineer used the Chelton MFD data and a simulation of the Lancair IV-TP to compute performance. The simulation matched the recorded GPS track and altitude, using a simple model, estimated weight of 3,628 lbs, recorded weather, and engine power data. The highest lift coefficient (CL) achieved in the simulation was about 1.03. The CLmax (flaps up) implied by stall speeds from flight tests was about 1.30, suggesting the maneuver required only about 79% of available lift and did not involve a stall. The maneuver was a steepening spiral dive with increasing roll, speed, and normal load factor reaching 7 G's and calibrated airspeed reaching 310 knots.
Pilot's Operating Handbook
An exemplar POH listed stall speeds: Vs=69 KCAS, Vso=61 KCAS, without specifying weight. Assuming maximum gross weight of the exemplar (3,200 lb), CLmax would be 2.03 flaps up and 2.59 flaps down, higher than flight test results. The POH emergency procedures section contained conflicting glide performance data: best glide speed 120 IAS with 1,570 fpm descent (7.7:1 glide ratio) but also stated glide distance approximately 0.75 nm per 1,000 feet (about 4.6:1 ratio).
Meteorological Information
Conditions over Oregon at 10,000 ft: south-southwest winds near 30 kts, temperature 3°C, dew point spread 2°C. At Roberts Field near the accident time: wind 090° at 7 knots, visibility 10 statute miles, clear skies, temperature 21°C, dew point 7°C, altimeter 29.93 inHg. Satellite data showed no thunderstorms or cumulonimbus activity; VMC prevailed. No advisories for turbulence or icing.
Communications
Redmond ATC recorded communications. The airplane was cleared for a left downwind departure from runway 10 and made no further transmissions until the accident. A series of transmissions from an unknown source included a grunt, a distant voice with one discernible expletive, and then no words.
Wreckage and Impact Information
The accident site was about 5 nm southeast of Sisters, Oregon, at 44°13.107'N, 121°30.547'W, elevation about 3,400 ft msl. Debris scattered over 1,600 feet on flat terrain with trees and brush. Heavier portions (cockpit, engine) at the west perimeter; other parts scattered on a heading of about 140° true.
Medical and Pathological Information
Autopsies of both pilots determined cause of death as massive blunt force trauma. Toxicological screenings detected ethanol in brain and muscle, possibly from sources other than ingestion due to tissue destruction and putrefaction. Both pilots had unreported medications Rosuvastatin and Metoprolol; cross-contamination was possible due to fragmentation.
Test and Research
The main wreckage consisted of cockpit and engine; wings had separated. Elevator flight controls remained attached. All major components accounted except the baggage door panel (hinges showed it was locked during breakup). Fragmentation prevented complete control continuity.
Engine examination revealed no evidence of pre-impact mechanical malfunction or failure. The propeller hub was disassembled; one of eight bolts was slightly bent. The shift of feedback ring indicated propeller blades were in the “BETA” range. Disassembly of the fuel control unit showed no anomalies. The fuel screen was clean. The examination found no mechanical issues that would have precluded normal operation.