Inola, OK, USA
N3187L
CESSNA 310J
The airplane’s most recent flight was about 9 months before the accident, and the pilot was flying the airplane on a ferry permit to another location to complete an overdue annual inspection. Before the accident flight, the airplane’s fuel tanks were topped off, and the pilot completed a preflight inspection that took about 1 hour. After taxiing to the runway area, the pilot returned to the ramp due to an unknown right engine issue. Following an extended engine run-up, the pilot taxied back to the runway and departed. Flight data showed that the airplane climbed to 5,800 ft mean sea level on an easterly heading, and about 1 minute before the accident, the airplane made a left turn to the north and began a rapid descent. For the last 23 seconds of the flight, the descent rate increased from about 1,000 to 30,000 ft per minute, and the ground speed varied between 151 and 198 knots. During the rapid descent and just before impact, the empennage and outboard wing sections separated. There were no emergency communications from the pilot and no witnesses to the accident. Distribution of the wreckage and damage signatures observed during postaccident examination were indicative of an in-flight breakup at low altitude due to the exceedance of structure design limitations. The left cockpit propeller control lever was found in the feathered position. Both propellers displayed indications consistent with low power; however, exact engine power levels could not be determined. In addition, both propellers had impact signature markings indicating blade positions at or near feather blade angles during the impact sequence. Although the airframe and engine examinations revealed no evidence of mechanical malfunctions or failures, the extensive impact damage precluded a functional examination of the flight controls. Investigators were unable to determine the reason for the loss of control and rapid descent based on the available evidence. The airframe and engine examinations revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Although the pilot tested positive for gabapentin, which is potentially sedating, tolerance to the sedating effects build quickly, and the pilot had likely been using the medication for some time. Thus, it is unlikely that any effects from the pilot’s use of gabapentin contributed to the circumstances of the accident.
HISTORY OF FLIGHTOn December 12, 2021, about 0931 central standard time, a Cessna 310J airplane, N3187L, was destroyed when it was involved in an accident near Inola, Oklahoma. The pilot sustained fatal injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 ferry flight. According to the airplane owner, he purchased the airplane in March 2020 and then became ill, which precluded him from flying the airplane. In March 2021, the owner requested a maintenance company at Tulsa International Airport (TUL) where the airplane was located to complete a required annual inspection, and the maintenance company performed a short maintenance test flight, which was the first flight since March 2020. Due to several discrepancies found during the initial inspection, which included airframe corrosion and a recommendation for both engines to be overhauled, the maintenance company would not complete the annual inspection without the discrepancies being corrected. Several months later, the owner then elected to hire the accident pilot, who was also a mechanic that had previously worked on the airplane, to ferry the airplane to North Carolina to complete the overdue annual inspection. Before the ferry flight, the airplane fuel tanks were topped off with fuel, and the pilot completed a preflight inspection that the owner estimated took about 1 hour. The pilot then started the engines and taxied the airplane for departure. A few minutes later, the owner, who was listening to air traffic control (ATC) communications on a handheld radio, heard the pilot inform ATC that he needed to return to the ramp/parking area due to an engine issue. The pilot called the owner via cellular phone and advised him of the situation. The owner observed the pilot complete an extensive engine run-up, and about 20 minutes later, the pilot taxied back for departure. The owner had no further communication with the pilot. A review of TUL ATC ground and tower communications revealed that at 0838, the pilot requested a visual flight rules (VFR) clearance for departure. At 0855, the pilot stated he needed to taxi back to parking due to “a miss on the right engine there pretty bad.” About 20 minutes later, the pilot contacted ground control and stated, “ready to go and try it again sir…we’ve got it cleared up enough.” TUL ground control cleared the pilot to taxi for departure. At 0921, the pilot was cleared for takeoff and told to execute a left turn to a 090° heading. At 0925, the pilot was cleared to an altitude of his discretion, and the pilot acknowledged a climb to 9,500 ft mean sea level (msl). At 0932:36, the TUL tower radar west controller terminated radar services and approved a frequency change for the flight. The pilot did not respond, and at 0932:43, the TUL controller again radioed the pilot and received no response. There were no further transmissions with the airplane. Automatic dependent surveillance-broadcast (ADS-B) data for the airplane began at 0922 and ended at 0931:11, about 21 miles east of TUL. The data showed the airplane climbed to 5,800 ft msl, and about 1 minute before the accident, the airplane made a left turn to the north and began a rapid descent (see figure 1). During the last 23 seconds of the flight, the descent rate increased from about 1,000 to 30,000 ft per minute; the ground speed varied between 151 and 198 knots; and the heading varied between 027° and 007°. Figure 1. Accident flight track About 1100, the airplane wreckage was located on a private ranch by personnel who were tending to cattle. There were no witnesses to the accident. PERSONNEL INFORMATIONThe pilot’s logbook was not located during the investigation, and his recent flight review and total flight time in the accident airplane make/model could not be determined. AIRCRAFT INFORMATIONAccording to a work order from the maintenance company that began the annual inspection in March 2021, one of the discrepancies listed was “Left hand Prop control will not feather.” In addition, the work order stated, “Inspection stopped. Aircraft unairworthy. Aircraft put back together for customer.” AIRPORT INFORMATIONAccording to a work order from the maintenance company that began the annual inspection in March 2021, one of the discrepancies listed was “Left hand Prop control will not feather.” In addition, the work order stated, “Inspection stopped. Aircraft unairworthy. Aircraft put back together for customer.” WRECKAGE AND IMPACT INFORMATIONPostaccident examination of the accident site revealed the airplane impacted terrain on a measured magnetic heading of about 060°, and the wreckage distribution field measured about 900 ft in length (see figure 2). Fragmented sections of the outboard wings, horizontal and vertical stabilizers, rudder, and elevators were the first components identified in the debris field. A large impact crater, consistent with the left engine and propeller assembly, was located about 300 ft from the fragmented empennage components. The left engine came to rest adjacent to the crater. Another large impact crater, consistent with the right engine and propeller assembly, was located about 300 ft from the left engine crater. The right engine came to rest adjacent to the crater. The main wreckage, which consisted of the inboard left and right wings, left and right engine nacelles, fuselage, and cockpit, was located about 300 ft from the right engine crater. Figure 2. Accident site Examination of the airplane revealed the main landing gear assemblies were retracted in the wing wheel wells. The cockpit flight and engine instruments were fragmented and destroyed. The cockpit throttle quadrant control levers were found in the following positions: Left and Right throttles – full forward, Left propeller – feather, Right propeller – full forward, and Left and Right mixtures – full forward. The empennage separated from the aft fuselage near the aft bulkhead location. The vertical stabilizer and a majority of the rudder remained attached to the empennage. The horizontal stabilizer and elevators separated from the empennage and fractured into multiple pieces. The horizontal rear spar was mostly intact; the structure forward of the left rear spar was deformed downward about 90°; and the outboard portion of the rear spar was twisted. The outboard left rear spar lower cap was rotated about 90° forward and up. The right rear spar was deformed forward and downward more than 90° from the centerline to the outboard section. The right and left wings outboard of the engines were highly fragmented. There was no obvious evidence of failure direction on any of the front spar segments, and no evidence of significant corrosion or pre-existing cracking was noted on any of the components. The extensive impact damage to the airframe precluded a functional examination of the flight controls. Due to extensive damage, both engines could not be functionally tested and were disassembled. The left engine would not rotate. Some metallic deposits were noted within the oil screen, pump drive gears, and oil bypass valve cap. All mechanical components within the engine displayed normal wear signatures. The origin of the deposits could not be determined. The right engine rotated by input through starter adapter. Mechanical continuity was noted throughout the right engine to all pistons, valves, and accessory gears. The magnetos for both engines were separated and could not be functionally tested due to damage. Examination of both propeller assemblies revealed no indications of any type of propeller failure or malfunction before impact. Both propellers displayed indications consistent with low power; however, exact engine power levels could not be determined. In addition, both propellers had impact signature markings indicating blade positions at or near feather blade angles during the impact sequence. COMMUNICATIONSFollowing the accident, a review of the air traffic control communications and procedures was conducted by the National Transportation Safety Board, Federal Aviation Administration (FAA), and the National Air Traffic Controllers Association. The group reviewed certified audio as provided by TUL and reviewed the Standard Terminal Automation Replacement System (STARS) replay of the accident as depicted on the radar display available to the air traffic controller working the accident flight. A review of the TUL STARS replay on the controller display revealed what keystrokes were made by the radar west (RW) controller and indicated what the airplane target displayed on the controller’s radar display. For the last 30 seconds of the flight, the airplane’s altitude decreased from 6,100 ft msl to 4,700 ft msl, followed by the code XXX, which indicated rapidly changing data. At 0931:21, the track was indicated as in a “coast” status, which occurs when the airplane is no longer giving a radar return. About 30 seconds later, the track was no longer active (ZZ status), and the STARS system would no longer predict the location of the target. At 0932:36, the RW controller informed the pilot that radar services were terminated and a frequency change was approved. The pilot did not respond and about 7 seconds later, the controller again called the accident pilot, and there was no response. The STARS replay also showed a VFR airplane conducting multiple passes at Claremore Regional Airport (GCM) about 5 nautical miles north of the final ADS-B target for the accident airplane. The STARS replay indicated that after the accident airplane went into ZZ status, the RW controller activated a quick look function (“beacon all” button) that pulled up the ADS-B unique Mode S assigned code and call sign for all airplanes on the display. The VFR airplane at GCM was determined not to be the accident airplane, and there were no other displayed aircraft near the accident airplane’s last location. The STARS replay noted that the RW controller had pushed the “beacon all” button ten times. No alert notice (ALNOT) was issued for the accident airplane. During an interview, the RW controller reported that he saw the accident airplane turning towards the northeast toward GCM, which was not uncommon in that area, and never observed the airplane in a descent. When he looked back, the track was in coast status, but he observed a primary target over GCM that he assumed was the accident airplane. MEDICAL AND PATHOLOGICAL INFORMATIONToxicology testing performed by the FAA’s Forensic Sciences Laboratory identified gabapentin in urine and liver tissue. Gabapentin is an antiseizure medication also commonly used to treat painful nerve conditions. The medication carries a warning about driving, sleepiness, and dizziness. According to the FAA, gabapentin is disqualifying for a medical certificate.
The loss of airplane control for reasons that could not be determined based on the available evidence.
Source: NTSB Aviation Accident Database
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