N2707JCessna 335 · 1979

On September 9, 2018, at 1037 eastern daylight time, a Cessna 335, N2707J, was destroyed when it was involved in an accident in Lake Worth, Florida. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The airplane had departed Key West International Airport (EYW), about 0936. A review of data recorded by the on-board engine monitor and the primary flight display revealed that, when the airplane was about 9 miles southwest of Palm Beach County Airpark (LNA), descending through an altitude of about 7,000 ft mean sea level (msl) at an airspeed of about 170 knots, the engine exhaust gas temperature (EGT) values for all cylinders on the left engine decreased to below 300°F, consistent with a total loss of engine power. About 2 minutes later, the values all increased to between 900°F and 1,100°F, where they remained for about 2 minutes. The EGT values then rose briefly to about 1,350°F before decreasing again to below 300°F, consistent with a second total loss of engine power. This second loss of engine power occurred as the airplane was on a left downwind leg abeam the runway 16 threshold at LNA, at an altitude of about 1,000 ft msl and an airspeed of about 110 knots. The right engine EGT values remained relatively constant about 1,300°F until the last 30 seconds of data, when they increased to about 1,400°F. The airplane maintained its heading and altitude for about 20 seconds after the loss of engine power before it entered left descending 180° turn. During this turn, the bank angle varied between 0 and 30°. About 5 seconds before the end of the recorded data, the airspeed decreased to about 73 knots, the bank angle increased and the airplane rolled inverted as its pitch increased to 76° nose down.

Several witnesses reported that while the airplane was on approach to runway 16 at LNA, it rolled back and forth, became inverted, then descended to the ground in a spiral and spin.

According to Federal Aviation Administration (FAA) airman records, the pilot did not possess a valid medical or airman certificate. He had previously held a private pilot certificate with ratings for airplane single and multiengine land; however, his certificate was revoked in 1997. His most recent second-class medical certificate was issued on June 30, 2014, and had expired for all classes in June 2016.

The pilot had owned the airplane since 2011. He received dual instruction in the accident airplane in 2011 and 2012, including one flight annotated in his logbook as "emergency procedures engine outs" in June 2011, and another annotated as "engine out procedures" in May 2012. In the 3 years preceding the accident, he logged 8.2 (2016), 6.4 (2017), and 1.8 (2018) hours in the accident airplane. There were no records of a flight review in his most recent logbook, which dated back to January 1997.

The airplane total time at the time of the accident could not be determined.

Recent Maintenance

Other than periodic inspections and oil changes, the most recent maintenance entry in the left engine logbook was recorded on September 3, 2014, noting the replacement of cylinder Nos. 1, 3, and 5. The airplane had accrued about 73 hours between this maintenance and the last annual inspection.

Other than periodic inspections and oil changes, the most recent maintenance entry for the right engine (found in the airframe logbook) was performed on June 21, 2018, noting the replacement of cylinder No. 3. That entry was made by the accident pilot, who was not a certificated mechanic. The airplane had accrued about 8 hours between this maintenance and the last annual inspection.

Fuel Information

The airplane was equipped with two main fuel tanks located in the wingtips (each with a capacity of 50 usable gallons), two auxiliary fuel tanks located in the wings (each with a capacity of 31.5 usable gallons), and one wing locker tank installed in the forward portion of the left engine baggage compartment (capacity 20 usable gallons). According to the airplane operating manual, the main tanks were to be used for takeoff, landing, descent, emergency, and the first 90 minutes of flight. The auxiliary tanks were to be used during level cruise flight only. The left wing locker tank did not supply fuel directly to either engine; instead, fuel could be transferred from the wing locker tank to the left main tip tank via an electric transfer pump using a switch in the cockpit. The engine fuel selector valve positions were off, main, auxiliary, and cross-feed.

The airplane was serviced with 50 gallons of fuel on September 5 at LNA, with an order to top off the main fuel tanks. The airplane flew from LNA to EYW uneventfully on September 6; the flight was about 62 minutes. The airplane was fueled with 47 gallons on September 9 at EYW, with an order to top off the auxiliary tanks. The accident flight was about 65 minutes long.

Fuel burn calculations estimated that the total fuel used on the accident flight was about 41 gallons.

Speed Limitations

According to the airplane operating manual, the minimum control speed, noted as "…the minimum flight speed at which the airplane is controllable with one engine inoperative and a 5° bank toward the operative engine," was 83 knots.

The airplane total time at the time of the accident could not be determined.

Recent Maintenance

Other than periodic inspections and oil changes, the most recent maintenance entry in the left engine logbook was recorded on September 3, 2014, noting the replacement of cylinder Nos. 1, 3, and 5. The airplane had accrued about 73 hours between this maintenance and the last annual inspection.

Other than periodic inspections and oil changes, the most recent maintenance entry for the right engine (found in the airframe logbook) was performed on June 21, 2018, noting the replacement of cylinder No. 3. That entry was made by the accident pilot, who was not a certificated mechanic. The airplane had accrued about 8 hours between this maintenance and the last annual inspection.

Fuel Information

The airplane was equipped with two main fuel tanks located in the wingtips (each with a capacity of 50 usable gallons), two auxiliary fuel tanks located in the wings (each with a capacity of 31.5 usable gallons), and one wing locker tank installed in the forward portion of the left engine baggage compartment (capacity 20 usable gallons). According to the airplane operating manual, the main tanks were to be used for takeoff, landing, descent, emergency, and the first 90 minutes of flight. The auxiliary tanks were to be used during level cruise flight only. The left wing locker tank did not supply fuel directly to either engine; instead, fuel could be transferred from the wing locker tank to the left main tip tank via an electric transfer pump using a switch in the cockpit. The engine fuel selector valve positions were off, main, auxiliary, and cross-feed.

The airplane was serviced with 50 gallons of fuel on September 5 at LNA, with an order to top off the main fuel tanks. The airplane flew from LNA to EYW uneventfully on September 6; the flight was about 62 minutes. The airplane was fueled with 47 gallons on September 9 at EYW, with an order to top off the auxiliary tanks. The accident flight was about 65 minutes long.

Fuel burn calculations estimated that the total fuel used on the accident flight was about 41 gallons.

Speed Limitations

According to the airplane operating manual, the minimum control speed, noted as "…the minimum flight speed at which the airplane is controllable with one engine inoperative and a 5° bank toward the operative engine," was 83 knots.

The airplane impacted trees and terrain in a park about 1 mile north of LNA. The main wreckage came to rest upright on a heading of about 030° magnetic. The airplane was partially consumed by a post-crash fire. The wreckage path was also oriented about 030° and was about 40 ft in length. The impact area was surrounded by trees; the only damage to branches were those directly above the main wreckage. A series of three ground scars consistent with propeller strikes were located on an asphalt jogging trail along a heading of 030°, which were aligned with and about 15 ft behind the right engine.

The wreckage sustained impact and fire damage; however, all major components of the airplane were present at the accident site. Flight control continuity was established from the cockpit controls to the flight control surfaces. The center and forward fuselage, as well as a large section of the left wing outboard of the left engine, were significantly damaged by postimpact fire. The aft fuselage was partially separated at the aft bulkhead, and the empennage was intact with only minor damage to the right horizontal stabilizer leading edge. The right wing was buckled downward near the right engine, and the leading edge was consumed by fire outboard of the right engine. The split-type flaps were partially extended. The landing gear actuator was found in the extended position.

All five fuel caps were intact and secure. The main fuel tanks were separated from the wing, with no damage to the attach fitting baffle. Both auxiliary fuel tanks were significantly fire damaged and partially consumed. The left wing locker fuel tank was intact and about 15 gallons of fuel were recovered from it. The left fuel selector valve was thermally damaged and remained attached to the wing. When air was applied, the valve was confirmed to be in the main tank position. The right fuel selector valve was thermally and mechanically damaged, remained attached to the control rod only, and appeared to be in the main tank position, but this could not be confirmed with an air test. Both of the cockpit fuel selector handles were found in the auxiliary tank position, the linkages between the handles and the valves were impact and fire damaged.

Both mixture controls were found near the cutoff position. The right propeller lever was near the low pitch position. The left propeller lever was near mid-travel. The right throttle was near the full-forward position. The left throttle was near mid-travel. All throttle quadrant control levers were folded over and bent toward the left.

The right engine remained attached to the wing and was impact and thermally damaged. The propeller remained attached to the engine. All three propeller blades were bent and twisted aft and displayed chordwise scratches and leading-edge gouges.

The left engine remained attached to the wing with its cowling intact and was impact and thermally damaged. All 6 cylinders produced thumb compression when the engine was rotated by hand. Valve train, camshaft, and crankshaft continuity were confirmed. A borescope examination of each cylinder revealed no anomalies. The oil filter was opened and contained no debris. Both magnetos produced spark on all towers when rotated with an electric drill. The top sparkplugs were removed, and all appeared "normal" in color and condition when compared to a Champion Check-a-Plug chart. The engine-driven fuel pump was impact damaged near the bellows. The drive coupling was intact, the pump rotated freely, and the vanes were intact. The fuel metering unit was intact with the control cable attached. The inlet screen was unobstructed. The fuel manifold was intact and its screen was unobstructed. The manifold cavity contained a small amount of debris, which was attracted to a test magnet. The ports in the cavity were unobstructed. The propeller was separated at the propeller flange. Two blades remained attached to the propeller hub, one of which was largely undamaged. The second blade was bent slightly about 8 inches from the root and again about 24 inches from the root; the blade displayed a slight twist. The third blade was separated from the hub and was largely undamaged. Examination of the left propeller assembly at the manufacturer's facility with oversight by the FAA revealed that the blades were at the low pitch stops at the time of impact. No anomalies were found.

Data recovered from the on-board engine monitor included parameters for each cylinder's head temperature and exhaust gas temperature, the turbocharger inlet temperature, and battery voltage. The unit typically records additional parameters such as fuel flow, engine RPM, engine manifold pressure, and engine oil temperature and pressure. It could not be determined if these parameters were not present due to the damage to the engine monitor (it could not be downloaded using the normal procedures for an intact unit) or if they were not connected when the unit was installed. The airplane was equipped with other non-recording instruments that displayed this information to the pilot.

The FAA Airplane Flying Handbook defined minimum control speed (Vmc) as:

The minimum flight speed at which the airplane is controllable with a bank of not more than 5 [degrees] into the operating engine when one engine suddenly becomes inoperative and the remaining engine is operating at takeoff power… At low airspeed and high-power conditions, the downward moving propeller blade of each engine develops more thrust than the upward moving blade…When the right engine is operative and the left engine is inoperative, the turning force is greater… In other words, directional control is more difficult when the left engine (the critical engine) is suddenly made inoperative.

An autopsy of the pilot was performed by the Office of the District Medical Examiner, District 15 – State of Florida; the cause of death was multiple blunt force injuries. Examination of the heart found calcified yellow plaques and green-brown grumous plaques in the native left anterior descending, left circumflex, and right coronary arteries, with luminal stenosis of greater than 75%, greater than 90%, and approximately 100%, respectively.

Toxicology testing performed on the pilot by the FAA Forensic Sciences Laboratory identified 0.132 (µg/mL) of diphenhydramine in cavity blood. Diphenhydramine is a sedating antihistamine available over-the-counter in many products used to treat colds, allergies, and insomnia. The therapeutic range is 0.0250 to 0.1120 ug/mL. It causes sedation and can result in impaired cognitive and psychomotor performance. Diphenhydramine undergoes postmortem distribution and central levels may be 3 times higher than peripheral levels.