History of Flight
On August 12, 2015, at about 0930 eastern daylight time, a Beech N35, registration N390Z, was destroyed when it impacted trees and terrain shortly after takeoff from Love's Landing (97FL) in Weirsdale, Florida. The airline transport pilot and a pilot-rated passenger were fatally injured. The airplane was operated by the pilot under 14 Code of Federal Regulations Part 91 for a personal flight to Page Field (FMY) in Fort Myers, Florida, with an instrument flight rules flight plan filed.
A witness, who was a pilot working near the departure end of runway 36, reported that the airplane took off from runway 36. The witness noted that airplanes using crossing runway 9/27 typically stayed low during takeoff, while those taking off from runway 36 usually climbed at a high angle to avoid traffic. The witness had observed the accident airplane take off many times from runway 36 using a high climb angle, but on the accident day, he was surprised not to see it climb above houses about halfway along the runway. When he finally saw the airplane about 300 to 400 feet before the departure end of the runway, it was about 50 feet in the air with landing gear retracted and level with the eaves of houses lining the runway. The witness then lost sight and heard two loud "bangs." The witness noted the engine sounded normal until takeoff, then started to "stall" as if a cylinder was "missing." When he saw the airplane, it appeared to be in ground effect, slow flight, and at a high angle of attack.
Personnel Information
The pilot, age 78, held an airline transport pilot certificate with single-engine land and multi-engine land ratings, a flight instructor certificate, a ground instructor certificate, a flight engineer certificate, and a mechanic certificate (airframe and powerplant). He held a third-class medical certificate with a corrective lenses restriction. According to his personal logbook, as of August 9, 2015, he had logged about 10,545 total hours, including 9,891 hours as pilot-in-command and 7,069 hours in single-engine airplanes. His most recent flight review was on July 19, 2014.
Aircraft Information
The four-seat, low-wing, retractable landing gear airplane was manufactured in 1961. It was powered by a 260-horsepower Continental IO-470-N reciprocating engine driving a Hartzell two-bladed constant-speed propeller. Maintenance logbooks showed the most recent annual inspection was completed on July 15, 2015, at an airframe total time of 6,663 hours. At the accident time, the airplane had accumulated about 5.5 hours since that inspection.
Meteorological Information
Weather observed at Leesburg International Airport (LEE), about 10 nautical miles east-southeast of the accident site, at 0853 included wind from 220° at 5 knots, visibility 10 statute miles, clear sky, temperature 28°C, dew point 24°C, and altimeter setting 30.01 inches of mercury.
Wreckage and Impact Information
The wreckage path began with broken tree branches about 40 feet up a tree located about 355° true and about 1,000 feet from the airport fence at the north end of the runway. The path continued at a downward angle of about 20° for about 130 feet to a ground impact mark containing the two-bladed propeller and spinner, which had separated from the engine crankshaft. One propeller blade exhibited "S" bending and blade twist signatures; the other had relatively light twisting. Both blades showed leading edge burnishing and chordwise scratching.
About 10 feet beyond the propeller, the airplane rested vertically against two trees, nose down, with the empennage bent over the fuselage. The right wing and cabin area were consumed in a postcrash fire; no evidence of inflight fire was found. The left wing and right ruddervator displayed tree impact marks. All flight control surfaces were accounted for, and control continuity was confirmed from cockpit to empennage and wings. The throttle and propeller controls were found full forward; the mixture control was pulled out about 1/2 inch from the panel bulkhead. The fuel boost pump switch was in the "ON" position and did not appear impact-damaged.
Engine crankshaft continuity was confirmed. Eleven of 12 spark plugs were examined and showed no anomalies; one plug was broken off in the cylinder and could not be removed. Five fuel injectors were found internally clear of debris; one had molten metal around it and could not be removed. The engine's throttle body metering unit was broken from its mount and held by fuel lines; the mixture control arm rotated on its shaft with no shaft movement. The unit was shipped to the manufacturer for further examination.
Medical and Pathological Information
Autopsies performed by the Office of the Medical Examiner, District 5, Leesburg, Florida, determined the pilot's cause of death as blunt force and thermal injuries, manner accident; the pilot-rated passenger's cause of death as multiple blunt force injuries, manner accident. Toxicology testing by the FAA's Bioaeronautical Research Sciences Laboratory found in the pilot 0.053 µg/ml diphenhydramine in blood and urine, ibuprofen in urine, 17% carbon monoxide in blood, and negative results for cyanide, ethanol, and major drugs of abuse. For the passenger, testing identified cetirizine, quinine, and tolterodine in liver and blood; negative for carbon monoxide, ethanol, and major drugs of abuse; cyanide testing not performed.
Tests and Research
The throttle body metering unit was examined on April 5, 2017, at the Continental Motors facility in Mobile, Alabama. It showed fire and impact damage, with fire damage more pronounced on the mixture side than the throttle side. The mixture and throttle control lever arms were secured by attachment nuts; after removal, the internal splines of both arms were stripped, and brass material from the bronze arms transferred to the external splines of the steel shafts. The arms were manufactured from bronze. According to the engine manufacturer, both lever arms should have been replaced with stainless steel arms per Continental Motors Category 2 Critical Service Bulletin (CSB) CSB08-3C, dated March 14, 2008. The CSB was issued after reports that bronze mixture and throttle control arms inadequately torqued could become loose, leading to loss of engine control or power.