WPR17FA151

A loss of control in flight for reasons that could not be determined based on the available information, which resulted in an in-flight breakup.

During the night multi-engine instructional flight in visual meteorological conditions, the flight instructor and private pilot receiving instruction reported their destination in sight to an air traffic controller and subsequently started a descent. A review of ground tracking radar information revealed that, following the initial descent, the airplane then climbed at over a 6,000 ft per minute (fpm) climb rate. Two seconds later, the airplane descended from 5,600 ft to 3,000 ft over 11 seconds, resulting in a descent rate in excess of 10,000 fpm. During the rapid descent, the airplane exceeded its published maximum structural cruising airspeed. The distribution of the wreckage was consistent with an in-flight breakup. Postaccident examination of the airframe revealed that the main wing spars fracture surfaces all exhibited a dull, grainy appearance consistent with overstress separation. There was no evidence of any pre-existing corrosion or cracking. Signatures observed throughout the wings were consistent with a positive load separation. Additionally, the stabilator spar fracture surfaces all displayed a dull, grainy appearance consistent with overstress separation. Signatures were consistent with the right stabilator separating in an upward direction and to the left. The left engine fuel selector valve handle was found in the "on" position, and the right engine fuel selector valve handle was in the "off" position; however, the fuel selector valve positions at the time of the accident could not be verified due to impact damage and mount separation at the fuselage, and whether the right engine fuel selector may have been intentionally turned off to simulate an engine failure could not be determined. Examination of the left engine carburetor revealed that two of the three float bays were partially filled with liquid. A float partially filled with liquid would allow the fuel flow into the carburetor float bowl to increase, and would result in a slightly rich condition, particularly at lower power settings. If a rich fuel-to-air mixture had existed, additional signatures would have been present within the engine exhaust and spark plugs, all of which exhibited normal operating signatures. No additional anomalies were found that would have precluded normal operation of the left or right engines. Toxicology testing of the flight instructor reported on the autopsy detected ethanol in liver; however, testing by the Federal Aviation Administration Forensic Sciences Laboratory did not identify ethanol in the urine. As no ethanol was detected in urine, the ethanol detected in the liver was most likely not ingested; therefore, effects from ethanol did not contribute to the accident. Additional toxicology tests detected evidence of use of the impairing psychoactive drugs marijuana and cocaine; however, no blood was available for testing. Cocaine is a strong stimulant and has significant adverse effects as the drug is metabolized, including agitation, anxiety, inability to focus on divided attention tasks, time distortion and poor balance and coordination. Cocaine's inactive metabolites, but not the active drug, was detected in tissues; it could not be determined when the flight instructor last used cocaine or if he was experiencing impairment from withdrawal symptoms. Additionally, the psychoactive component of marijuana was detected in tissues, but because no blood was available for testing, determination of the instructor's possible impairment from marijuana at the time of the accident was not possible. The circumstances of the accident are consistent with an in-flight loss of control. Whether and to what extent the flight instructor's use of the two psychoactive drugs some time before the accident degraded his performance and contributed to his inability to safely manage the flight could not be determined.

Recorded weather observation data from Daytona Beach International Airport (DAB), Daytona Beach, Florida, located about 30 miles south of the accident site, at 2253 included wind from 090° at 3 knots, 10 statute miles visibility, a broken cloud layer at 25,000 ft, temperature 28°C, dew point 26°C, and an altimeter setting of 30.15 inches of mercury. Flight Instructor The flight instructor, age 70, held an airline transport pilot certificate with airplane single-engine land and airplane single-engine sea ratings, along with commercial pilot privileges for airplane multi-engine land and glider. He also held a flight instructor certificate with airplane single- and multi-engine and instrument ratings. A third-class FAA airman medical certificate was issued to the instructor on June 4, 2016, with the limitation, "must have available glasses for near vision." On the application for that medical certificate, the instructor reported 34,830 total hours of flight experience, of which 400 hours were in the previous 6 months. The flight instructor's logbook was not located. Pilot Receiving Instruction The pilot receiving instruction, age 27, held a private pilot certificate with airplane single-engine land and instrument airplane ratings. He was issued a second-class FAA medical certificate on August 17, 2016 with no limitations. A review of flight school records revealed that, as of July 12, 2017, he had accumulated 131.2 hours of flight experience, of which 7 hours were in multi-engine airplanes. The airplane impacted terrain about 25 miles north of OMN. The main wreckage came to rest inverted within a heavily wooded area. Trees directly above the wreckage were broken, consistent with little to no forward movement of the airplane at impact. The outboard portions of the left and right wings, baggage door, and a portion of the right side of the stabilator were located throughout a 0.5-mile-long and 0.2-mile-wide debris path in water and marshland northwest of the main wreckage. The fuselage came to rest inverted on a heading about 022° magnetic. Various debris, including fragments of the left stabilator, were located within about 50 ft of the fuselage. The wreckage was recovered to a secure location for further examination. Fuselage Examination of the recovered wreckage revealed that the roof structure was compressed into the cabin seating area. The fuselage was partially separated at fuselage station (FS) 156. The instrument panel was crushed aft into the front seat area. The cabin door and baggage area door were separated. Both the left and right inboard portion of the wings remained attached to the fuselage structure. Both left and right seat control wheel horns were fragmented. The T-bar remained attached to the fuselage hinge point. The horizontal section was fragmented. The aileron control cables remained attached to the T-bar chain. The stabilator cables remained attached to the T-bar assembly. The rudder pedals were impact damaged. The rudder cables remained attached to the rudder cable assembly. The left engine fuel selector valve lever was in the "on" position, and the right engine fuel selector valve lever was in the "off" position. The fuel selector valve positions could not be verified due to impact damage and mount separation at the fuselage. Air was applied to the fuel selector valves and continuity was established throughout each valve. Left Wing The outboard left wing was recovered about 0.48 mile west-northwest of the main wreckage. The main spar was fractured about wing station (WS) 105. The fiberglass wingtip was separated from the outboard wing at WS 206.7 and recovered mostly intact and undamaged. The left aileron was separated from the left outboard wing at the hinge points. Three sections of the left aileron were recovered, spanning from the inboard end about WS 106 to about WS 181. The outboard portion (25 inches) of the left aileron, including the aileron balance weight, was not recovered. The main spar, leading edge, and upper and lower skins between about WS 105 and WS 130 were damaged and deformed up and aft indicative of an upward (positive) separation of the left outboard wing. There were several fractures and twisting deformation of the main spar structure in this area. The main spar inboard of the fracture point, between about WS 93 and WS 105, was deformed aft and down. A semicircular impact impression and tree debris were embedded in the wing structure in this area. The aileron cables remained attached to the bellcrank and there was tearing of the WS 93 rib in an aft direction at the normal cable pass-through locations. The fractured ends of the aileron control and balance cables had a splayed appearance consistent with tension overload. The main spar fracture surfaces all had a dull, grainy appearance consistent with overstress separation. There was no evidence of any pre-existing corrosion or cracking on any of the fracture surfaces. Right Wing A large portion of the right outboard wing was recovered about 0.39 mile west-northwest of the main wreckage. The main spar upper cap was fractured about WS 126 and the lower cap was fractured about WS 148. The leading edge nose skin and ribs and lower leading edge skin were separated as a unit from the right outboard wing and recovered about 0.6 mile west-northwest of the main wreckage. A smaller piece of the leading edge lower skin about 3 ft long was also separated outboard of WS 170. The fiberglass wingtip was separated from the outboard wing at WS 206.7 and only the upper half was recovered. The right aileron was separated from the wing at the hinge points. The entire aileron was recovered; however, it was separated into two pieces at the center hinge point. The main spar inboard of the fracture point was deformed up and aft outboard of WS 105, indicative of an upward (positive) separation of the right outboard wing. The aileron cables remained attached to the bellcrank and there were two cable tears through the upper wing skin inboard of the fracture point. The fractured ends of the aileron control and balance cables had a splayed, broomstraw appearance consistent with tension overload. The main spar fracture surfaces all exhibited a dull, grainy appearance consistent with overstress separation. There was no evidence of any pre-existing corrosion or cracking on any of the fracture surfaces. Empennage The vertical stabilizer was separated from the fuselage but remained connected to the fuselage by the electrical wiring. The two vertical stabilizer forward spar bolts remained installed in the stabilizer; however, they were pulled through the fuselage fitting in an upward direction. The vertical stabilizer rear attach fitting remained attached to the fuselage and was deformed aft and to the left. All the rivets that attached the fitting to the vertical stabilizer rear spar were sheared. The rudder was separated from the vertical stabilizer at the hinge points and was recovered at the main wreckage site. The rudder trim tab remained attached. The upper 12 to 18 inches of the vertical stabilizer and rudder were damaged and deformed to the left. The horizontal stabilator hinge and counterweight was torn from the upper end of the vertical stabilizer and recovered at the main wreckage site. The left stabilator was torn into several pieces and was found wrapped around a tree at the main wreckage site. The left 28 inches and the center 29 inches of the trim tab were separated from the stabilator and recovered at the main wreckage site. The right side of the stabilator was separated from the empennage and recovered mostly intact about 0.6 mile west-northwest of the main wreckage. About 47 inches of the trim tab remained attached to the right stabilator. The right stabilator skins were buckled and there were impact impressions in the leading edge. The stabilator spar was fractured about right buttock line 7. The upper spar cap and upp