N6945QBeech A23-24 · 1968

On December 10, 2023, about 1019 central standard time, a Beech A23-24 airplane, N6945Q, was destroyed when it was involved in an accident near Oklahoma City, Oklahoma. The pilot and his passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

According to recordings of air traffic control (ATC) communications at Wiley Post Airport (PWA), Oklahoma City, Oklahoma, at 1008:16, the pilot established contact with the ground controller and requested a visual flight rules (VFR) departure to the north. At 1008:42, the ground controller issued a taxi clearance to runway 35R via taxiway C1, cleared the airplane to cross runway 31, and asked the pilot if he wanted VFR flight following. At 1008:48, the pilot told the ground controller that he did not need VFR flight following and then correctly read back the taxi clearance.

At 1015:37, the pilot contacted the tower controller and stated that he was holding short of runway 35R on taxiway A1 and was ready to depart to the north under VFR. At 1015:44, the tower controller cleared the pilot for takeoff on runway 35R.

A review of ADS-B track data revealed that the airplane’s liftoff occurred before midfield and the airplane was climbing though 350 ft above ground level (agl) as it flew over the end of runway 35R.

At 1016:57, a security camera located on a hangar near the east end of taxiway A5 captured the airplane in a climb from runway 35R. As the airplane continued the climb to the north there was possible evidence of intermittent smoke trailing behind the airplane.

According to ADS-B track data, after takeoff the airplane continued the climb while on a north ground track, as shown in figure 1. At 1018:21, the airplane entered a left turn and about 3 seconds later the pilot told the tower controller, “… we’re a return for landing.”

At 1018:33, the tower controller cleared the pilot to enter a left downwind for runway 35R. At 1018:38, the pilot transmitted, “okay, we are losing power [unintelligible] tower I’m gonna land on [unintelligible].” During the pilot’s transmission, the engine was heard in the background running roughly.

Figure 1. Plot of airplane flight track data.

At 1018:43, the airplane was about halfway through a 180° turn toward the airport when it began a descent from the flight’s maximum altitude of about 2,165 ft mean sea level (msl), as shown in figures 2 and 3. At that time, the airplane was about 1.7 nautical mile (nm) from the runway 17R threshold and 882 ft above the runway threshold height. According to the Beech A23-24 Pilot Operating Handbook, the airplane’s maximum glide was achieved at the best glide airspeed of 82 knots with the flaps up and the propeller control full aft. If properly configured and flown, the airplane’s glide distance in a zero-wind condition was about 1.7 nm per 1,000 ft of altitude above terrain.

At 1018:51, the pilot stated “… I’m declaring an emergency.” The tower controller subsequently cleared the pilot to land on the runway of his choice. At 1019:29, the tower controller stated that the surface wind was from 320° at 5 knots.

The ADS-B flight track data showed the airplane continued to descend toward the airport and runway 17R. At 1019:50, the final ADS-B return was recorded about 0.4 nm north of the runway 17R threshold at an altitude of about 1,445 ft msl. At that time, the airplane was about 162 ft agl, 68 knots calibrated airspeed, and descending about 1,355 feet per minute (fpm).

The same security camera that captured the airplane’s takeoff from runway 35R also captured the airplane as it descended toward the airport. At 1019:13, the video footage showed the airplane descending with light colored smoke trailing the airplane. At 1020:04, dark smoke began rising from the accident site location.

Two witnesses reported smoke trailing from the airplane and that the engine was running roughly before the accident. One witness noted that the trailing smoke was a gray/white color. A third witness stated that the engine was sputtering as the airplane flew over his position and then it made a 180° turn toward the airport.

Figure 2. Plots of airplane altitude, ground speed, true airspeed, calibrated airspeed, and

vertical speed.

Figure 3. Plots of airplane heading, roll angle, and flight path angle.

The pilot’s flight logbook was not located during the investigation.

According to FAA documentation, just over two months before the accident, on October 7, 2023, the pilot passed his private pilot check ride that was administered by an FAA Designated Examiner. On his application for the pilot certificate, the pilot reported a total flight time of 80.2 hours, of which 10 hours were flown as pilot-in-command.

Based on recorded ADS-B flight track data, the airplane was flown at least 17.5 hours after the pilot purchased the airplane on June 30, 2023. Of that total, about 9.5 hours were flown after the pilot received his private pilot certificate on October 7, 2023.

According to available maintenance documentation, the last major overhaul of the Lycoming IO-360-A2B engine, s/n L-3904-51A, was completed on June 6, 2005, at 398.92 hours (all logbook entries were based on tachometer time). At the time of the overhaul, the engine had accumulated 924.9 hours since new.

On December 24, 2008, at 637.78 hours, all four cylinders were removed and overhauled due to low cylinder compression and excessive oil consumption. Postaccident calculations based on previous tachometer readings indicated that the engine had 238.86 hours since major overhaul (SMOH) when the cylinders were overhauled.

On January 12, 2021, the recording tachometer was rebuilt, reset to 0.0 hours, and then reinstalled in the airplane. Postaccident calculations based on previous tachometer readings indicated that the airframe total time (AFTT) and engine SMOH were 1,397.91 hours and 474.48 hours, respectively.

On April 15, 2023, at 209.3 hours, 683.78 hours SMOH, the engine oil and oil filter were replaced, No. 1 cylinder was serviced due to low compression. The No. 1 cylinder bore was honed, and new gaskets and hold-down nuts were installed. The airplane was returned to service following an engine ground run and subsequent test flight that did not reveal any oil leaks or anomalies. The associated engine log entry indicated that the engine was inspected in accordance with an annual inspection and determined to be in an airworthy condition.

Also completed on April 15, 2023, was the airplane’s last annual inspection. Postaccident calculations based on previous tachometer readings indicated that the AFTT and engine SMOH were 1,607.21 hours and 683.78 hours, respectively.

According to FAA registration records, the pilot purchased the airplane on June 30, 2023. A prepurchase inspection report, dated June 22, 2023, at 210.1 hours, completed by an aviation mechanic from Twin Aviation Repair, LLC, Douglas, Georgia, indicated that the AFTT and engine SMOH were 1,585.31 hours and 684.5 hours, respectively. However, based on postaccident calculations based on previous tachometer readings indicated the AFTT was 1,608.01 hours.

On November 3, 2023, at 225.0 hours, 699.48 hours SMOH, the engine oil and oil filter were replaced, and an oil sample was submitted to a laboratory for analysis. The airplane was returned to service following an engine test run that did not reveal any oil leaks or anomalies.

The oil analysis report, dated December 5, 2023, indicated elevated levels of aluminum, chromium, and iron. The laboratory commented that there was “a lot of metal in this sample” and that internal corrosion could be an issue if the airplane had been sitting. The laboratory suggested a borescope inspection, compression test, monitor oil temperature, and check the oil filter for evidence of metal. Additionally, the laboratory report stated that excessive oil consumption could also be an indication of engine issues.

On December 5, 2023, the aviation mechanic who submitted the oil sample sent the pilot/owner an email to discuss the results of the oil sample that was collected on November 3, 2023, during the last oil change. The mechanic wrote that the oil sample had high level of chrome and that it might be from internal corrosion and possibly attributable to cylinder wear. The mechanic also acknowledged that the cylinder compression values during the prepurchase inspection were nominal and that there had been recent cylinder work completed. As such, the mechanic recommended recurring 25-hours oil sample analyses, and 50-hour compression checks with borescope inspections until the chrome levels trended down to normal levels. The pilot/owner agreed and told the mechanic that he would advise him when the airplane had flown 25 hours since the last oil change.

On December 1, 2023, at 233.9 hours, an E-Z Heat oil sump heater was installed on the engine. Postaccident calculations based on previous tachometer readings indicated that the AFTT and engine SMOH were 1,631.81 hours and 708.38 hours, respectively. The aviation mechanics who installed oil sump heater stated that the back screws of the lower cowling were removed to gain access underneath the engine to install the oil-sump heater, but none of the engine oil system components were loosened or removed to gain access to the engine sump.

The airplane’s recording tachometer was destroyed by the postimpact fire, which prevented calculation of the airplane’s airframe and engine times at the time of the accident.

According to available maintenance documentation, the last major overhaul of the Lycoming IO-360-A2B engine, s/n L-3904-51A, was completed on June 6, 2005, at 398.92 hours (all logbook entries were based on tachometer time). At the time of the overhaul, the engine had accumulated 924.9 hours since new.

On December 24, 2008, at 637.78 hours, all four cylinders were removed and overhauled due to low cylinder compression and excessive oil consumption. Postaccident calculations based on previous tachometer readings indicated that the engine had 238.86 hours since major overhaul (SMOH) when the cylinders were overhauled.

On January 12, 2021, the recording tachometer was rebuilt, reset to 0.0 hours, and then reinstalled in the airplane. Postaccident calculations based on previous tachometer readings indicated that the airframe total time (AFTT) and engine SMOH were 1,397.91 hours and 474.48 hours, respectively.

On April 15, 2023, at 209.3 hours, 683.78 hours SMOH, the engine oil and oil filter were replaced, No. 1 cylinder was serviced due to low compression. The No. 1 cylinder bore was honed, and new gaskets and hold-down nuts were installed. The airplane was returned to service following an engine ground run and subsequent test flight that did not reveal any oil leaks or anomalies. The associated engine log entry indicated that the engine was inspected in accordance with an annual inspection and determined to be in an airworthy condition.

Also completed on April 15, 2023, was the airplane’s last annual inspection. Postaccident calculations based on previous tachometer readings indicated that the AFTT and engine SMOH were 1,607.21 hours and 683.78 hours, respectively.

According to FAA registration records, the pilot purchased the airplane on June 30, 2023. A prepurchase inspection report, dated June 22, 2023, at 210.1 hours, completed by an aviation mechanic from Twin Aviation Repair, LLC, Douglas, Georgia, indicated that the AFTT and engine SMOH were 1,585.31 hours and 684.5 hours, respectively. However, based on postaccident calculations based on previous tachometer readings indicated the AFTT was 1,608.01 hours.

On November 3, 2023, at 225.0 hours, 699.48 hours SMOH, the engine oil and oil filter were replaced, and an oil sample was submitted to a laboratory for analysis. The airplane was returned to service following an engine test run that did not reveal any oil leaks or anomalies.

The oil analysis report, dated December 5, 2023, indicated elevated levels of aluminum, chromium, and iron. The laboratory commented that there was “a lot of metal in this sample” and that internal corrosion could be an issue if the airplane had been sitting. The laboratory suggested a borescope inspection, compression test, monitor oil temperature, and check the oil filter for evidence of metal. Additionally, the laboratory report stated that excessive oil consumption could also be an indication of engine issues.

On December 5, 2023, the aviation mechanic who submitted the oil sample sent the pilot/owner an email to discuss the results of the oil sample that was collected on November 3, 2023, during the last oil change. The mechanic wrote that the oil sample had high level of chrome and that it might be from internal corrosion and possibly attributable to cylinder wear. The mechanic also acknowledged that the cylinder compression values during the prepurchase inspection were nominal and that there had been recent cylinder work completed. As such, the mechanic recommended recurring 25-hours oil sample analyses, and 50-hour compression checks with borescope inspections until the chrome levels trended down to normal levels. The pilot/owner agreed and told the mechanic that he would advise him when the airplane had flown 25 hours since the last oil change.

On December 1, 2023, at 233.9 hours, an E-Z Heat oil sump heater was installed on the engine. Postaccident calculations based on previous tachometer readings indicated that the AFTT and engine SMOH were 1,631.81 hours and 708.38 hours, respectively. The aviation mechanics who installed oil sump heater stated that the back screws of the lower cowling were removed to gain access underneath the engine to install the oil-sump heater, but none of the engine oil system components were loosened or removed to gain access to the engine sump.

The airplane’s recording tachometer was destroyed by the postimpact fire, which prevented calculation of the airplane’s airframe and engine times at the time of the accident.

The airplane impacted a 15-foot-tall pile of concrete rubble at a concrete recycling facility on an approximate 180° heading. The upper portion of nose landing gear, the nose gear fork, nose wheel and tire, and the right main landing gear were found separated among the top of the rubble, as shown in figure 4. Tire markings and red paint transfer (matching the aircraft color) were observed on multiple pieces of concrete. One of the tire tracks was outlined by an oily substance consistent with engine oil. The fractured nose gear segment and nose wheel tire were coated with a thin layer of what appeared to be engine oil, as shown in figure 5. The right lower portion of the cowling, also coated with oil, came to rest next to the nose gear segment. The outboard 6 ft of the right wing fracture separated and came to rest inverted at the bottom of the rubble pile and sustained significant thermal damage that consumed portions of the skin.

The main wreckage came to rest in an open grass area on a south-southwest heading about 40 ft beyond the concrete rubble pile, as shown in figure 6. The accident site elevation was 1,286 ft msl. The main wreckage consisted of the fuselage, engine, propeller, left wing, inboard portion of the right wing, and tail section. The left main landing gear separated from the wing and was found about 60 ft past the main wreckage. All structural components and flight control surfaces were located at the accident site.

The extensive postimpact fire thermally damaged a majority of the airplane, including the fuselage skin and structure. The inboard portion of the right wing separated at the wing root and came to rest beside the fuselage. Thermally damaged portions of the horizontal stabilator and the tail beacon were identified beneath the fire damaged section of the cockpit and right wing. The upper surface of the right wing’s integral fuel tank was consumed by fire. The left wing’s upper skins forward of the main spar, from the root to the aileron, were mostly consumed by fire.

An examination of the flight control system was limited due to the extent of thermal damage; however, there was no evidence of a flight control cable separation. The flap selector assembly was found in the flaps retracted position. The airframe examination revealed no evidence of a preimpact mechanical malfunction or failure that would have precluded normal operation.

Figure 4. Accident site overview. (Aerial photo provided by Oklahoma City PD)

Figure 5. Nose landing gear fork, wheel, and tire covered in engine oil.

Figure 6. Main wreckage at the accident site.

The airplane was normally parked in a hangar located at the southeast corner of PWA. Examination of the hangar revealed 11 empty 1-quart bottles of Aeroshell W100 engine oil. Additionally, there was evidence of non-recent minor oil puddling on the asphalt floor and a discernible nose wheel tire tread track in the congealed oil.

There was no evidence of an oil leak on the asphalt between the hangar door and the unmarked asphalt taxiway alongside the row of hangars.

There was evidence of a significant oil leak and puddling on the unmarked asphalt taxiway, as shown in figure 7, consistent with the airplane being stationary for an extended period with the engine running. Additionally, there was evidence of oil spray from the propeller wash blowing oil aft. A discernible, dark black, oily, tire track extended from the oil puddle toward taxiway C1.

There was evidence of a smaller oil puddle near where the unmarked asphalt taxiway transitioned onto concrete taxiway C1.

There was evidence of oil drips and nose wheel tire tracks on taxiway C1. The oil drips and nose wheel track continued to the runup pad.

There was evidence of a significant oil leak and puddling on the runup pad, consistent with the airplane being stationary for an extended period with the engine running. Additionally, there was evidence of oil spray caused by the propeller wash blowing oil aft.

Additional oil drips and nose wheel tire tracks were evident on a path from the runup pad toward the hold short lines for runway 35R.

There was evidence of an oil leak where the airplane came to stop before the hold short lines for runway 35R.

Figure 7. Evidence of oil leak and nose wheel tire tread track outside of the hangar.

The engine remained attached to the mounts, and the mount remained attached to the firewall. The engine sustained thermal damage during the postimpact fire. The exhaust was crushed upward and aft. The rear of the oil sump and lower portion of the accessory case were consumed by the fire. There was an opening punched out of the top of the engine case inboard of the No. 2 cylinder base. There were also multiple holes punched out of the lower side of the engine case inside the oil sump, between cylinder Nos. 1 and 2. Connecting rods Nos. 1, 2, and 3 were found broken and deformed. Numerous pieces of connecting rod, rod caps, and rod bolts were found in the remaining portion of engine oil sump. There was a crack of the forward lower left crankcase between the base of cylinder No. 2 and the case split. Visual examination inside of the crankcase (through the crankcase holes and by borescope inspection) and the cylinder rocker boxes revealed an overall lack of oil wetting of the internal drivetrain components, consistent with a prolonged exposure to the postimpact fire.

The remote-mounted oil filter assembly was found thermally deformed. The oil filter was safety tied with 0.02-inch safety wire. The oil hoses were found thermally damaged and separated from the remote oil filter assembly and the filter adapter. The aluminum fittings were found melted. The oil cooler was also mostly consumed by fire with only the center core remaining. The oil cooler hoses were found separated from the oil cooler assembly with their attachment fittings mostly consumed by fire. Both the supply and return hose ends at the oil cooler assembly contained resolidified aluminum, consistent with the fittings being in place during the postimpact fire. The oil cooler hoses remained attached at the rear of the engine. All oil and fuel hoses were thermally compromised.

A borescope inspection of the cylinders revealed no anomalies. The No. 2 exhaust push rod shroud tube was found dislodged. Numerous shroud tubes were thermally deformed. All oil drain-back tubes exhibited significant thermal damage consistent with prolonged exposure to fire.

The propeller governor drive adapter was found dislodged from the accessory case. The propeller governor was mostly consumed by fire. The propeller governor oil line separated from the steel fitting at the governor and where it returned into the crankcase, with both aluminum B-nuts consumed by fire.

Both magnetos were found thermally deformed. All ignition leads were thermally damaged. The top spark plugs electrodes appeared worn, with a dark sooty appearance.

The fuel servo was found fractured separated from its flange. The servo was found partially thermally deformed. The throttle and mixture cables remained attached to their respective control arms. The flow divider was found partially deformed, with the diaphragm consumed by fire. The engine-driven fuel pump was also found thermally damaged.

The propeller remained attached to the engine crankshaft. The pitch change mechanism and spring were separated from the front of the hub. The blades remained attached and did not move freely. The outboard third of Blade A melted along the trailing edge. The blade was bent aft about 10° midspan. Blade B was bent forward 10° midspan. Neither blade exhibited leading edge scoring or gouging.

The pilot was taken to a hospital where resuscitative efforts were unsuccessful, and he was subsequently declared dead at 1911 on the day of the accident. The Oklahoma Office of the Chief Medical Examiner performed the pilot’s autopsy. According to the pilot’s autopsy report, the cause of death was thermal injuries, and the manner of death was accident.

The Oklahoma Office of the Chief Medical Examiner performed toxicological testing of a hospital blood draw that was obtained from the pilot at 1056 on the morning of the accident. This toxicological testing did not detect any tested-for substances, which included ethanol, opiates, fentanyl, and benzodiazepines.

The pilot’s postmortem toxicological testing, conducted by the FAA Forensic Sciences Laboratory, detected morphine, fentanyl, midazolam, lidocaine, etomidate, and propofol in femoral blood and urine. Norfentanyl was detected in urine, but norfentanyl testing in femoral blood was inconclusive. Naproxen was detected in femoral blood but not in urine.

The toxicological specimens tested by the FAA Forensic Sciences Laboratory were postmortem specimens, collected after the pilot’s postaccident medical care. All detected substances are commonly administered during medical care following major injury.