History of Flight
On December 10, 2011, about 1258 mountain standard time, an experimental, amateur-built Van's RV-7A, N724WD, was substantially damaged when it impacted terrain near Surprise, Arizona, shortly after the pilot reported a problem in cruise flight. The certificated private pilot, who was also the builder and owner of the airplane, was fatally injured. The personal flight was operated under 14 CFR Part 91. Visual meteorological conditions prevailed, and no flight plan was filed.
The airplane departed Glendale Municipal Airport (GEU), Glendale, Arizona, about 1226. Luke Air Force Base (LUF) was located about 5 miles west of GEU. LUF ground tracking radar data captured the entire flight. The radar first acquired the airplane at 1227:27 as it climbed through 1,300 feet mean sea level (msl), broadcasting transponder code 1200. The airplane flew about 25 miles northwest of GEU, maneuvered briefly, then tracked back toward GEU. Altitude varied between about 2,700 and 3,300 feet msl.
About 1255:50, about 12 miles northwest of GEU, the airplane began decelerating from 100 knots ground speed. It slowed to about 60 knots and began a descent. At 1256:25, at 2,500 feet, the first 7700 beacon code was received. The pilot transmitted a "mayday" call to LUF Approach about 25 seconds later, stating he had a problem and was "going down." No further communications were received, and the final radar return was at 1257:21.
A flight instructor and student flying in the vicinity heard the pilot's radio calls. They visually located the wreckage and guided a first responder helicopter to the site about 45 minutes after the accident.
Personnel Information
According to FAA records, the pilot held a private pilot certificate with a single-engine land rating. His most recent FAA third-class medical certificate was issued July 2010, and his most recent flight review was completed January 2011.
The pilot's flight logbook indicated about 713 hours total flight experience. He conducted the first flight and all FAA Stage 1 testing of the airplane, accruing about 340 hours in it over 5 years and 2 months. The logbook contained only one explicit reference to aerodynamic stalls, dated November 24, 2006, when the pilot had about 21 hours in the airplane. It also referenced multiple mechanical issues not in the maintenance records.
Persons familiar with the pilot's flying habits described him as a "straight and level flyer" who disliked stalls and did not perform aerobatics.
FAA Civil Aeromedical Institute toxicology tests detected no carbon monoxide, cyanide, ethanol, or screened drugs. The Maricopa County Office of the Medical Examiner reported the cause of death as "blunt impact injuries."
Aircraft Information
The airplane was built in 2006 by the pilot. Airframe maintenance records showed no significant problems. A hangar mate was unaware of any unusual issues.
It was powered by an Eggenfellner conversion of a Subaru EJ-25 series automobile engine—a 4-cylinder, liquid-cooled unit with electric fuel pump, electronic ignition, and electronic fuel metering, monitored by an engine control module (ECM). Engine maintenance records showed no significant problems; no pre-installation time-in-service records were found.
The engine had an Eggenfellner "Generation III" propeller speed reduction unit (PSRU) and a Quinti-Avio propeller hub with electrically-controlled pitch adjustment for three Warp Drive composite blades. No significant problems were noted in propeller maintenance records.
Meteorological Information
The GEU 1247 automated weather observation reported wind from 080 degrees at 5 knots, visibility 20 miles, broken clouds at 20,000 feet, temperature 19°C, dew point -7°C, and altimeter 30.10 inches of mercury.
Wreckage and Impact Information
The airplane came to rest upright on level hard desert terrain with moderate vegetation. The wreckage was tightly contained; only a few non-structural components separated. Ground scars were consistent with impact at essentially the same location. The canopy was found just forward of the wreckage. The nose was severely crushed up and aft. Propeller blades showed no rotational scoring; all three were at a similar pitch setting. Visual examination of the engine and PSRU revealed no pre-impact anomalies. Continuity from propeller hub to engine was established.
All three fixed landing gear were deformed up and aft. The cockpit area was severely deformed, with fuselage fractures at the firewall and aft of the cabin bulkhead. The cockpit longitudinal axis faced about 248 degrees magnetic; the aft fuselage was about 36 degrees tail-right relative to the forward section.
Both wings exhibited leading-edge crush damage up and aft across their full span, consistent with an impact angle of about 50 degrees nose-down. Ailerons remained attached. Flaps were retracted at impact. Damage indicated contact between the right wing and flap inboard edges and the fuselage sidewall. The right rear spar was fracture-separated at its attach point; examination at the NTSB Materials Laboratory found no pre-impact failures.
The horizontal and vertical stabilizers remained attached. Elevators and rudder were attached. The elevator trim tab clevis was fractured; laboratory examination determined it failed due to overstress, with no material deficiencies.
Three of four rivets securing the left rudder stop were sheared, allowing rudder overtravel to the left and contact with the left elevator. Damage indicated the elevator trim tab was likely displaced beyond normal travel.
Control continuity for flaps, ailerons, rudder, and elevator was established except for the elevator trim system, whose pre-impact condition could not be determined.
The airplane had a Trio Avionics "EZ Pilot" single-axis autopilot. Its power toggle switch was found in the down/off position. No angle-of-attack or stall warning system was installed. The ELT was found fragmented in the aft fuselage. No pre- or post-impact fire was observed.
Additional Information
Airplane Flight Profile
Data from LUF radar and the onboard GPS unit reconstructed the flight profile. The meandering ground track was consistent with hand flying. After the northwest turnaround, the airplane tracked southeast toward GEU. Between 1255:50 and 1256:15, groundspeed decreased from 100 to 60 knots. From 1256:15 to 1257:15, it descended from about 2,800 to 2,000 feet msl. At 1256:25, transponder switched to 7700 at 62 knots and 2,700 feet. The mayday at 1256:53 occurred at 50 knots and 2,300 feet. Groundspeed continued decreasing, and a turn south began about 1256:55. At 1257:15, descent rate exceeded 2,000 fpm, and data ended shortly after. Terrain elevation was about 1,300 feet msl.
Airspeed and Stall Information
As an experimental amateur-built aircraft, flight testing was required for airspeed calibration and stall speed determination. The Vans Construction Manual outlined requirements. Comparison of the airspeed indicator (ASI) arcs to published values showed that the ASI full-flaps stall speed was 48 knots versus Vans' 50 knots, and no-flaps stall speed was 50 knots versus 56 knots. No records of airspeed calibration or stall speed testing were found; accuracy of the ASI markings and actual stall speeds could not be determined.
The manual noted that in most RVs, there is little pre-stall buffet, occurring within a few mph of the fully developed stall. The airplane lacked a stall warning system.
Engine Electrical Information
Eggenfellner Aircraft ceased production about 2010. The installation manual emphasized that the engine requires constant, stable electrical power. The manual depicted three master switches controlling three buses: Engine, Main, and Avionics. The accident airplane had three labeled master switches: "Master," "Avionics Master," and a three-position "Bus Master" toggle (ON, OFF, OVERRIDE). Comparisons suggested the Bus Master likely controlled engine power: ON powered Engine Bus via Main master; OFF isolated it; OVERRIDE powered it independent of Main master setting.
The day after the accident, the Main and Avionics master switches were found off; the Bus Master was in OVERRIDE. The investigation could not determine if any first responders reset switch positions.
Communications
The flight departed GEU, which had an operating control tower, but after departure the pilot was not required to communicate until return. Since the accident occurred before re-contact, no GEU communications were obtained.
The bulk of the flight was in the Luke Air Force Base Special Air Traffic Rule (SATR) North Area, which was not active at the time. The pilot squawked 1200 for almost the entire flight. At 1256:25, he switched to 7700. At 1256:53, he transmitted "Luke approach, Luke approach, mayday, mayday 724WD right by the substation, I have a (uncertain word) that's out of control." The uncertain word sounded like "flap," "craft," or "prop." At 1257:00, LUF approach assigned a discrete code and requested intentions. At 1257:05, the pilot transmitted that he was "going down," and no further transmissions were received. Recorded communications were clear with no background noise.
The NTSB investigator-in-charge obtained radar data and recordings 4 days after the accident, after on-scene examinations were completed.