Reason for engine’s failure a mystery
Federal investigators have determined that a failed engine likely caused a pilot to lose control of his plane and crash west of Cody last year. However, after months of investigation, the National Transportation Safety Board (NTSB) was unable to figure out why the left engine of the rented Cessna T310R stopped working.
Four people — pilot Don Scott, his friend Joyce Bartoo of Washington, D.C., his sister Diane J. Stubbs and her husband Gerald B. Stubbs of Maryland — all died in the July 18, 2015, crash.
Scott was a 66-year-old Denver attorney with some 570 hours of prior flying experience. He’d taken the group for an unplanned detour over Yellowstone National Park as they flew from Sheridan to Billings.
After circling Yellowstone, Scott got permission from air traffic control to continue toward Billings; the air traffic controller directed Scott to climb from 13,300 to 15,000 feet shortly before noon.
Several minutes later, air controllers lost contact with Scott and the plane, which turned southeast toward Cody and began plummeting.
In what the NTSB described as an apparent “near-vertical” dive, the Cessna crashed into a wooded area west of the Mooncrest Ranch and roughly 10 miles northwest of the Buffalo Bill Reservoir.
The airplane was smashed into pieces and caught on fire.
“It is likely that the left engine was not operating at the time of impact,” the NTSB wrote in its final April 14 report on the accident, adding, “The pilot likely lost control of the airplane following the loss of left engine power.”
The NTSB did not reach a conclusion about what caused the engine to stop working.
At the time Scott was directed to climb to 15,000 feet, there was an active weather advisory — called an AIRMET — that icing could occur between 14,000 and 22,000 feet.
“The (air traffic) controller did not provide this information to the pilot, and it could not be determined if the pilot was aware of the AIRMET,” the NTSB wrote in its report. The report adds that, “although the airplane was operating in an area conducive to aircraft icing, the reason for the loss of engine power could not be determined during post-accident examinations.”
Original article can be found here: http://www.powelltribune.com
Independence Aviation LLC: http://registry.faa.gov/N72TP
NTSB Identification: CEN15FA307
14 CFR Part 91: General Aviation
Accident occurred Saturday, July 18, 2015 in Cody, WY
Probable Cause Approval Date: 04/14/2016
Aircraft: CESSNA T310R, registration: N72TP
Injuries: 4 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
After flying over Yellowstone National Park at 13,500 ft, the pilot requested an instrument flight rules (IFR) clearance direct to Billings Logan International Airport (BIL), Billings, Montana. At that time, the airplane was at 13,300 ft and was below the minimum en route altitude of 14,400 ft. After confirming that the pilot could maintain terrain and obstacle clearance, the controller issued an IFR clearance direct to BIL (to the north-northeast) and instructed the pilot to climb to and maintain 15,000 ft. An AIRMET was in effect for icing between 14,000 ft and FL (flight level) 220 in the area; the controller did not provide this information to the pilot, and it could not be determined if the pilot was aware of the AIRMET. After the airplane reached 15,000 ft, the controller made a radar handoff and attempted to transfer radio communications, but the pilot did not respond. The controller stated that the airplane turned east and began a rapid descent. The airplane impacted a creek bed in heavily wooded mountainous terrain at an elevation of 7,762 ft. Tree heights were about 100 ft. There was a scrape mark on the side of one tree, and another tree had the top broken off. No other trees were damaged, consistent with the airplane having descended through the tree canopy in a near-vertical attitude. The airplane was severely fragmented and had been exposed to a postimpact fire.
The wreckage, engines, propellers and turbochargers were subsequently examined. The left propeller bore evidence of little or no rotation. Disassembly revealed it was in the “low pitch/high rpm” position. Disassembly of the left engine revealed no anomalies. The left engine turbocharger turbine bore no rotational marks and could not be rotated. No rub marks were noted on the turbine housing. It is likely that the left engine was not operating at the time of impact. The outboard end of the recovered right propeller blade bore chordwise scratches. Disassembly of the right engine revealed no anomalies. The right engine turbocharger turbine rotated freely when turned by hand. The pilot likely lost control of the airplane following the loss of left engine power. Although the airplane was operating in an area conducive to aircraft icing, the reason for the loss of engine power could not be determined during postaccident examinations.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot's loss of airplane control following the loss of power in the left engine; the reason for the loss of power could not be determined during postaccident engine examination.
HISTORY OF FLIGHT
On July 18, 2015, at 1154 mountain daylight time, a Cessna T310R airplane, N72TP, impacted mountainous terrain near Cody, Wyoming. The pilot and three passengers were fatally injured. The airplane was destroyed. The airplane was registered to and operated by Independence Aviation LLC, Englewood, Colorado, under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Day visual meteorological conditions (VMC) prevailed at the time, and an instrument flight rules (IFR) flight plan had been air filed. The flight originated from the Sheridan County Airport (SHR), Sheridan, Wyoming, about 1030 and was destined for the Billings Logan International Airport (BIL), Billings, Montana.
According to Independence Aviation Dispatch papers, the pilot rented the airplane on July 16, 2015, at 0900, and was scheduled to return on July 21, 2015, at 1800. The passengers included the pilot's girlfriend, his sister (both of the latter retired attorneys) and her husband. Their travel itinerary between July 16 and July 17 is unknown. The airplane arrived at SHR at some time on July 17. They departed SHR on July 18 about 1030.
Radar track data indicated that N72TP departed SHR in VMC conditions, turned to a westerly heading, and flew over Yellowstone National Park at 13,500 feet. It then turned south and then east and flew back over the Park. At 1148, the pilot contacted the Salt Lake Air Route Traffic Control Center (ARTCC-ZLC) R16 controller and requested an IFR clearance direct to BIL. At that time, the airplane was still at 13,300 feet. The R16 controller issued a beacon code and identified the airplane on radar but he did not issue a current altimeter setting or confirm its mode C altitude. N72TP was below the minimum IFR altitude of 14,400 feet. After confirming the pilot could maintain terrain and obstacle clearance, the controller issued an IFR clearance direct to BIL and instructed the pilot to climb and maintain 15,000 feet. The controller did not advise the pilot of an AIRMET (airmen meteorology) in effect in that area for icing between 14,000 feet and FL (flight level) 220 (22,000 feet).
At 1154, the R16 controller made a radar handoff after N72TP had attained 15,000 feet and attempted to transfer radio communications. There was no response. N72TP was seen to turn east and then southeast in a rapid descent and in the direction of Cody. A low altitude alert was not issued and N72TP was not advised that radar contact had been lost. The R16 controller attempted to contact N72TP several times, and asked another aircraft to attempt to contact the airplane. When radar and radio contact was lost, the airplane was on the 253° radial from the COD (COD) VORTAC (Very High Frequency Omnidirectional Radio Range) at 21 DME (Distance Measuring Equipment) miles. ZLC then contacted the Park County 911 Communications Center and issued an Alert Notice (ALNOT) 23 minutes after radar and radio contact was lost.
PERSONNEL (CREW) INFORMATION
The pilot, age 66, held a commercial pilot certificate with airplane multiengine and instrument ratings, and private pilot privileges with a airplane single-engine land rating. He also held a third class airman medical certificate, dated June 9, 2015, with no restrictions or limitations. According to his application for this medical certificate, the pilot estimated he had accrued 571 total flight hours. According to a spokesman for Independence Aviation, their records indicated the pilot had logged 162.7 hours in the Cessna 310.
N72TP (serial number 310R1628), a model T310R, was manufactured by the Cessna Aircraft Company in 1979. It was equipped with two Continental TSIO-520-EB engines (serial numbers 206174-9-E, left; 244934-R, right), each rated at 300 horsepower, driving two Hartzell 3-blade, all-metal, constant speed, full-feathering Q-tip propellers (left propeller: model number FC7693DF, serial number EB030B; blade 1, K76440; blade 2, K76441; blade 3, K76443). Only the outboard portion of one blade was recovered from the right propeller assembly. Both engines were equipped with Kelly Aerospace (formerly Hartzell, Garrett Allied Signal) turbochargers.
The following pertinent METAR (Meteorological Terminal Aviation Routine Weather Report) was recorded by the Automated Weather Observing System (ASOS-3) at Yellowstone Regional Airport (KCOD):
Wind, 010° at 5 knots; visibility, 10 miles; sky condition, clear; temperature, 16° Celsius (C.); dew point, 6° C.; altimeter, 30.19 inches of mercury.
There was an AIRMET in effect for icing between 14,000 feet and FL (flight level) 220 (22,000 feet) in the area.
WRECKAGE AND IMPACT INFORMATION
The wreckage was located 1.5 miles west of the Mooncrest Ranch, north of the Buffalo Bill Reservoir, and 4 miles east of 12,244-foot Trout Peak. The airplane had impacted a creek bed in heavily wooded mountainous terrain about 21 miles west-northwest of Cody, Wyoming, at an elevation of 7,762 feet. Tree heights were about 100 feet. There was a scrape mark on the side of one tree, and another tree had the top broken off. No other trees were damaged, consistent with the airplane having descended through the tree canopy in a near vertical attitude. The debris scatter was aligned on a magnetic heading of 230° degrees. Portions of all main components of the airplane -- including both tip tanks, portions of the main fuselage, portions of the horizontal stabilizer and elevator, the vertical stabilizer and rudder, portions of both wings, both engines, and both propellers -- were located in the immediate area of the accident.
The airplane was severely fragmented and had been exposed to a post-impact fire. Trees in the immediate vicinity were also fire damaged. Due to the extensive fragmentation of the airplane, photo documentation of the wreckage was made. The wreckage was then recovered and transported to Beegles Aircraft Service, in Greeley, Colorado, for further examination.
MEDICAL AND PATHOLOGICAL INFORMATION
Autopsies were performed on the pilot and the three passengers by Forensic Medicine and Pathology, Billings, Montana. According to the pilot's autopsy report, death was attributed to multiple blunt force traumas. The pilot's toxicology report revealed no ethanol in the liver and muscle tissue. Ibuprofen and solifenacin were detected in the liver (solifenacin is used in the treatment of contraction of an overactive bladder with associated problems such as increased urination frequency and urge incontinence). Carbon monoxide and cyanide tests were not performed.
TESTS AND RESEARCH
On December 7 and 8, 2015, the engines, propellers, and turbochargers were disassembled and examined at Continental Motors, Mobile, Alabama.
The left propeller bore evidence of little or no rotation. Disassembly revealed it was in the LOW PITCH/HIGH RPM position. Disassembly of the left engine revealed no anomalies. The engine-driven fuel pump vanes were intact, but could only be partially when rotated by hand. There was no evidence of oil starvation. The rod bearings appeared normal. The turbocharger turbine bore no rotational marks. The turbine and compressor could not be rotated. No rub marks were noted on the turbine housing. The compressor bore impact crush damage. The wastegate operated normally.
The outboard end of the recovered right propeller blade bore chordwise scratches. Disassembly of the right engine revealed no anomalies. The engine-driven fuel coupling was sheared. The coupling was taken to Continental's metallurgical laboratory for analysis. According to their report, "the fractured surfaces showed evidence of mechanical overload" and "did not exhibit signs of extended contact or rotation after separation." The turbocharger turbine rotated freely when turned by hand. There was some metal splatter noted on the turbine housing. The compressor bore impact crush damage and could not be rotated. The wastegate operated normally.
The wreckage was released to the insurance adjuster on January 29, 2016.
In addition to the Federal Aviation Administration, parties to the investigation include Textron Aviation (formerly Cessna), Continental Motors, Hartzell Propeller, and RAM Aircraft.