N900AW

HISTORY OF FLIGHTOn December 8, 2022, about 1810 eastern standard time, a Beech A36, N900AW, was substantially damaged when it was involved in an accident near Covington, Georgia. The commercial pilot and pilot-rated passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

Before departure from Griffin-Spalding County Airport (6A2), Griffin, Georgia, en route to Dekalb-Peachtree Airport, Atlanta, Georgia, the pilot-rated passenger checked the engine oil quantity and determined it to be 10 quarts. After takeoff, the left-seat pilot levelled the airplane at 5,500 ft mean sea level. Both pilots then heard a loud bang from the engine and observed a shower of sparks from the cowling, and the engine lost power. The pilots engaged the Garmin Smart Glide mode of the autopilot, and as designed the autopilot pitched up to attain and maintain best glide airspeed; it then advised that no airports were within glide range. Control of the airplane was then transferred to the pilot-rated passenger, who disengaged the autopilot. He declared an emergency while looking for a suitable landing site. The pilot maneuvered for a forced landing on a section of the road that appeared to be straight. Soon after asking the left-seat pilot to lower the flaps, the airplane’s left wing impacted part of a tree that was growing over the roadway. The airplane then touched down on the road and impacted 2 street signs before coming to rest in a ditch on the right side of the road.

Engine data associated with the accident flight revealed the oil pressure was normal until about 1801, when extensive fluctuations occurred over the next 5 minutes but with the oil pressure remaining about 40 psi. At 1806, the engine rpm dropped to about 1,000 rpm, with a corresponding decrease of oil pressure, and a corresponding drop in exhaust gas temperatures and cylinder head temperatures. Then the rpm and oil pressure stabilized with the oil pressure remaining about 40 psi until about 1808:24. About that time, the oil pressure and engine rpm began decreasing to 0 psi oil pressure and 0 engine rpm. AIRCRAFT INFORMATIONThe airplane was equipped with a Garmin GDU 460, a Garmin GDU 470, and a Garmin GTN 750. The panel-mounted GPS receivers were retained for read-out by the National Transportation Safety Board (NTSB) Vehicle Recorder Division.

The airplane’s Pilot’s Operating Handbook and FAA Approved Airplane Flight Manual (POH/AFM) specified that the minimum oil pressure at idle was 10 psi. The engine manufacturer’s Installation and Operation Manual (IOM) specified that the normal oil pressure (30 to 60 psi) was required between oil temperature of 75°Fahrenheit (F) to 240°F, while the minimum oil pressure at idle (600 rpm) was specified to be 10 psi when the oil temperature was at or below 240° F. A warning in the IOM manual associated with low oil pressure specified that if it dropped below 30 psi, an engine failure was imminent and to follow the procedures in the POH/AFM. The warning also indicated that if the oil pressure dropped suddenly from a normal indication of between 30 and 60 psi, the pilot should monitor oil temperature closely and land as soon as possible.

The engine manufacturer’s Standard Practice Maintenance Manual had a warning that stated the following: “Operation with insufficient oil pressure may result in a catastrophic engine failure. Engines operated with oil pressure below the specified limitation, must be disassembled, inspected, and repaired as necessary to ensure the engine was safe for operation.”

The airplane’s engine maintenance records revealed that a new engine was installed on the airplane in 2017. However, it was disassembled in 2018 due to a propeller strike; after repair, it was reinstalled on the airplane. Between 2018 and November 27, 2022, normal maintenance occurred with no engine lubrication system issues reported.

On November 27, 2022, after having avionics work performed, which included the installation of a standby alternator, two pilots (both of whom were on the accident flight), boarded the airplane at 6A2 with the intention of flying to Cedar Ridge Airport (GA62), Griffin, Georgia, where an annual inspection was to be performed.

According to the NTSB Electronic Flight Information System Specialist’s Factual Report, at 1636:40, while on the ground stationary with the engine rpm about 2,000, the oil pressure began to decrease from about 50 psi. While stationary, the oil pressure dropped to 9 psi at 1638:43. About 1 minute later with the oil pressure at 6 psi, the airplane began to taxi towards the approach end of the runway. During the takeoff roll at 1643:15, the oil pressure was 3 psi while the oil temperature was in the normal range at 152° F. The airplane became airborne and one of the pilots reported the engine “waivered” with the oil pressure at 3 psi, the oil temperature at 181° F, and the engine rpm at 2,720. The pilot of another airplane at 6A2 radioed them and advised smoke was trailing the airplane. The flight returned to 6A2 and landed uneventfully, with the engine rpm reaching 0 at 1645:52. After landing, oil was found all over the bottom of the fuselage and in a very large pool on the taxiway where they had performed the first engine run-up to test the recently installed standby alternator.

The maintenance facility that had installed the standby alternator examined the engine. A borescope inspection of the engine was performed and just over 4 quarts of oil remained in the engine. The remaining engine oil was drained, and the oil filter element was examined with no discrepancies reported.

The examination revealed that the standby alternator had not been torqued properly, resulting in the subsequent oil leak. A replacement standby alternator was installed and properly torqued. There was no maintenance entry made in the engine logbook for the oil and oil filter change after the diminished oil pressure. One of the pilots of the November 27th flight communicated what had occurred concerning the low oil pressure with the facility that had improperly installed the standby alternator and with the facility that planned to perform the annual inspection.

The airplane was subsequently flown on November 29th from 6A2 to Cedar Ridge Airport (GA62), Griffin, Georgia, for the annual inspection. A review of engine data associated with the flight revealed normal engine oil pressure for the majority of recorded data with the exception of one point when the oil pressure dropped below 30 psi. During the annual inspection, the engine oil was drained through a 1,000-ppm strainer. While the engine logbook entry for the annual inspection indicated that no contamination was found in the oil filter element, an invoice associated with the inspection indicated, “Removed and cut filter with light metal debris found.” A new oil filter was installed and 11 quarts of oil were added. Additionally, a borescope inspection of the engine was performed with no discrepancies reported.

After the annual inspection was completed on December 7th, the airplane was flown from GA62 to 6A2. A review of engine data associated with the flight revealed normal engine oil pressure throughout the flight.

Based on maintenance records and downloaded data associated with the repositioning flight the day before the accident, at the start of the accident flight, the engine had accrued about 6 hours since the flight on November 27, 2022, when it had been operated at near-zero oil pressure and high rpm. AIRPORT INFORMATIONThe airplane was equipped with a Garmin GDU 460, a Garmin GDU 470, and a Garmin GTN 750. The panel-mounted GPS receivers were retained for read-out by the National Transportation Safety Board (NTSB) Vehicle Recorder Division.

The airplane’s Pilot’s Operating Handbook and FAA Approved Airplane Flight Manual (POH/AFM) specified that the minimum oil pressure at idle was 10 psi. The engine manufacturer’s Installation and Operation Manual (IOM) specified that the normal oil pressure (30 to 60 psi) was required between oil temperature of 75°Fahrenheit (F) to 240°F, while the minimum oil pressure at idle (600 rpm) was specified to be 10 psi when the oil temperature was at or below 240° F. A warning in the IOM manual associated with low oil pressure specified that if it dropped below 30 psi, an engine failure was imminent and to follow the procedures in the POH/AFM. The warning also indicated that if the oil pressure dropped suddenly from a normal indication of between 30 and 60 psi, the pilot should monitor oil temperature closely and land as soon as possible.

The engine manufacturer’s Standard Practice Maintenance Manual had a warning that stated the following: “Operation with insufficient oil pressure may result in a catastrophic engine failure. Engines operated with oil pressure below the specified limitation, must be disassembled, inspected, and repaired as necessary to ensure the engine was safe for operation.”

The airplane’s engine maintenance records revealed that a new engine was installed on the airplane in 2017. However, it was disassembled in 2018 due to a propeller strike; after repair, it was reinstalled on the airplane. Between 2018 and November 27, 2022, normal maintenance occurred with no engine lubrication system issues reported.

On November 27, 2022, after having avionics work performed, which included the installation of a standby alternator, two pilots (both of whom were on the accident flight), boarded the airplane at 6A2 with the intention of flying to Cedar Ridge Airport (GA62), Griffin, Georgia, where an annual inspection was to be performed.

According to the NTSB Electronic Flight Information System Specialist’s Factual Report, at 1636:40, while on the ground stationary with the engine rpm about 2,000, the oil pressure began to decrease from about 50 psi. While stationary, the oil pressure dropped to 9 psi at 1638:43. About 1 minute later with the oil pressure...