N101GCessna 310R · 1974

On October 29, 2020, about 0939 Pacific daylight time, a Cessna 310, N101G was destroyed when it was involved in an accident near Henderson, Nevada. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

Automatic dependent surveillance–broadcast (ADS-B) data indicate that the airplane departed from runway 12 at North Las Vegas Airport (VGT), Las Vegas, Nevada, at 0929 and proceeded to fly on a southeast heading for about 1 minute before turning toward the southwest. The pilot’s intended destination was Gillespie Field Airport (SEE), San Diego/El Cajon, California. At 0930, approximately 1 mile south of VGT at an altitude of 2,800 ft, the pilot contacted Las Vegas Term Terminal Radar Control and requested a change of destination to Henderson Executive Airport (HND), Henderson, Nevada.

At 0935, the pilot requested to proceed direct to HND and stated that he needed to shut down one engine. The controller approved the request and transferred communication to HND tower controllers. No further communication was received from the pilot. ADS-B data indicate that, about the time of the pilot’s request to proceed to HND, the airplane turned to the east then southeast before data was lost at 0938. When the airplane began the turn to the east, the airspeed was approximately 86 knots. The airspeed briefly increased to 97 knots over the next minute, then gradually decreased to a final airspeed of 78 knots when the data was lost.

The final portion of the accident flight was captured by a video taken on a cell phone by a witness and another video from a home security camera. The security camera video showed the airplane rolled to the left before ground impact followed by a postcrash fire. Examination of the cell phone video at the National Transportation Safety Board’s (NTSB) Vehicle Recorders Laboratory found the left propeller was not turning before ground impact and the right propeller was turning.

Another witness later reported observing the airplane fly south as it crossed a highway. According to the witness, it appeared as if the airplane attempted to gain altitude (while losing airspeed) as it avoided hitting powerlines that ran across the highway. The airplane appeared to nose down after crossing the powerlines then maintained its altitude for approximately 1,000 ft. Shortly after, the airplane nosed down again, rolled “hard left,” and impacted the ground. The witness stated that the left engine appeared to be inoperable as the propeller was not spinning. Additionally, the airplane was flying about 15° to 20° right wing down before it rolled to the left and impacted the ground.

A postaccident examination of the left engine revealed it separated from the airframe upon impact; visual examination of the engine revealed extensive thermal and impact damage. It also revealed two holes in the crankcase above cylinder Nos. 3 and 4.

Both magnetos remained attached to their respective installation points; however, the impulse coupling assembly exhibited extensive thermal and impact damage and could not be tested for sparks. Both magnetos were disassembled, and no anomalies were noted. The spark plugs all remained installed in their respective cylinders and were undamaged. The top spark plugs were removed and visually inspected; their electrodes all appeared to have normal wear. The fuel pump was removed and examined. The fuel drive coupling was intact; however, the fuel pump could not be rotated by hand due to the impact damage. The oil pump remained secured to its respective installation point, and no anomalies were noted with the pump.

All six cylinders remained attached to the engine and sustained damage consistent with the impact and thermal exposure. A borescope inspection performed on each cylinder revealed the intake and exhaust valve heads on each cylinder displayed normal operating and combustion signatures. The top and bottom throughbolts on cylinder No. 5, as well as the top throughbolt on cylinder No. 3, exposed threads between the respective nuts and the corresponding cylinder decks. The No. 2 connecting rod was separated from the crankshaft. All six piston faces displayed normal operating and combustion signatures and all the piston rings were undamaged and free in their respective grooves.

The crankcase was opened, and indications of fretting were present on main bearing Nos. 2 and 3. Additionally, no indication of lubrication was noted. The No. 2 main bearing was laterally displaced, indicating there was some bearing movement.

The left engine three-blade propeller separated at the crankshaft propeller flange. Two of the blades remained straight with no bending or twisting deformation. One blade was slightly bent as a result of the impact.

Examination of the right engine revealed signatures of power at the time of the accident.

The following components from the left engine were sent to the NTSB Materials Laboratory for further examination: inserts for main bearing Nos. 1 – 5, inserts for connecting rod bearings Nos. 1, 2, 3, 5, and 6, and a thrust bearing. The components were manufactured by both Continental Motors and Superior Air Parts. Several of the inserts exhibited features consistent with heat exposure. The number 4 main bearing inserts exhibited heavy rubbing damage and metal had filled in much of the bearing groove, obstructing five of the six oil through-holes. All of the main bearing left inserts exhibited features consistent with melted and resolidified metal near the insert end face.

Examination of maintenance records revealed an entry dated January 29, 2020, stating the left engine was “disassembled and inspected for low oil pressure.” The entry stated: “alternator failure – metal caused oil pressure problem.” According to the entry, the connecting rod nuts and bolts were replaced, and the main bearings and rod bearings were replaced. Additionally, the alternator, oil cooler, and starter adapter were replaced with overhauled units. The engine was reassembled, test run, and reinstalled on the airplane on January 31, 2020, at a Hobbs time of 1,157.1 hours, and 1,002.2 hours since major overhaul.

The most recent annual examination was completed on April 18, 2020, at a Hobbs time of 1,197.2 hours. The entry in the logbook for the examination indicated cylinder compressions were: 1/62, 2/61, 3/64, 4/65, 5/62, and 6/64. The entry also stated the engine magneto to engine timing was checked and adjusted, and the spark plugs were serviced.

The last entry in the left engine logbook was dated August 3, 2020, for an oil change. The last Hobbs time recorded at the oil change was 1,250.4 hours.

Examination of the pilot’s logbook revealed he flew the accident airplane 24.6 hours since the oil change.

Federal Aviation Administration (FAA) Advisory Circular (AC) No. 43.13-1B, “Acceptable Methods, Techniques, and Practices – Aircraft Inspection and Repair,” states in part: “If cylinder has less than a 60/80 reading on the differential test gauges on a hot engine, and procedures in paragraphs 8-15b(5)(i) and (j) fail to raise the compression reading, the cylinder must be removed and inspected.” According to the AC, when performing a differential compression test, cylinders should be pressurized to 80 pounds per square inch (psi).

The minimum controllable speed (VMC), as defined by the FAA Airplane Flying Handbook (FAA-H-8083-3B), is the minimum speed at which directional control can be maintained (under a specific set of circumstances), with the critical engine inoperative. The VMC for the Cessna 310 is 80 knots.

A fuel receipt provided by personnel at VGT revealed the pilot purchased 115 gallons of 100LL fuel at 0912 on the morning of the accident.

The Clark County, Nevada Coroner performed an autopsy on the pilot. The autopsy listed the cause of death as “blunt trauma.” Toxicology testing performed by the forensic pathologist detected ethanol in the pilot’s liver tissue at 0.200 grams per hectogram (gm/hg).

Toxicology testing performed at the FAA Forensic Sciences Laboratory detected ethanol in the pilot’s muscle tissue at 0.015 gm/hg; ethanol was not detected in his brain tissue. The antihistamine diphenhydramine was detected in the pilot’s urine and liver tissue.

Ethanol is a social drug commonly consumed by drinking beer, wine, or liquor. It acts as a central nervous system depressant; it impairs judgment, psychomotor functioning, and vigilance. Ethanol can also be produced after death by microbial activity. Diphenhydramine is a sedating antihistamine (commonly marketed as Benadryl) and is available over the counter in many products used to treat colds, allergies, and insomnia. Diphenhydramine carries the warning that use of the medication may impair mental and physical ability to perform potentially hazardous tasks, including driving or operating heavy machinery.