PIPER PA-32R-300

Full Narrative

HISTORY OF FLIGHTOn October 22, 2021, about 1557 eastern daylight time, a Piper PA-32R-300 airplane, N1652H, was destroyed when it was involved in an accident near Walterboro, South Carolina. The pilot was seriously injured, and the passenger was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight.
The airplane departed on an 802 nautical mile flight from Shannon Airport (EZF), Fredericksburg, Virginia, about 1256 destined for Miami Executive Airport (TMB), Miami, Florida. Before departure, the pilot brought the airplane’s fuel tanks up to their total fuel capacity of 98 gallons by adding 78.81 gallons of 100LL aviation gasoline.
The flight was uneventful until about 2 hours and 53 minutes into the flight, when the airplane was in cruise at 6,000 feet above mean sea level (msl). The pilot advised air traffic control (ATC) that he wanted to divert to Lowcountry Regional Airport (RBW), Walterboro, South Carolina, for fuel, and then resume his IFR flight plan to TMB.
The air traffic controller then cleared the pilot to fly direct to RBW and approved him to leave the frequency to get the current weather and NOTAMS for the airport. When the pilot reported that he was back on frequency, the air traffic controller instructed him to maintain 3,000 feet msl and to state his approach request. The pilot requested the visual approach to runway 23. The air traffic controller then instructed the pilot to maintain 1,600 feet msl, and subsequently instructed him to fly heading 190° to the RBW Airport.
The airplane was approximately nine miles north of RBW when the airplane began to descend without a clearance. The pilot then declared “Mayday” and reported a “lagging engine” to which the air traffic controller advised that RBW was at one o’clock and seven miles, and to maintain present heading and altitude.
The minimum safe altitude warning then activated at the air traffic controller’s station as the airplane descended through 1,000 feet msl. The air traffic controller queried the pilot if they were reporting a rough running engine, to which there was no response. The airplane continued descending while in a left turn to the northeast and was last observed by ATC radar at an altitude of 100 feet msl. There was no further communication with the pilot.
According to a witness, he heard an airplane “sputter and stop.” He looked in the direction of the airplane, and continued to hear sputtering, before the sound of an engine cut out, and then sputtering again. The airplane kept flying and then went out of sight.
According to two other witnesses, about 1556, they began to hear an engine noise. They observed [the accident airplane] almost directly above the tree line behind their neighbor’s house. It appeared to be in a left turn, and then they next heard a loud “pop” from the airplane and the engine noise ceased.
According to the pilot, once he arrived at the airport, he pulled the airplane out of the hangar with his tug, loaded their baggage, boarded the airplane, and then started the engine. He then taxied to the fuel pumps. He filled both wing tanks all the way up (just below the caps). He then took off. The weather was VMC and he had filed an instrument flight rules flight plan. He planned to cruise at 6,000 feet and he could not remember if he changed altitude at any time during the cruise portion of the flight.
He had filed the flight as one leg. About 1.5 hours into the flight, he decided to land for fuel due to the headwinds he encountered. He had also made the decision to get fuel early, as he would be landing at his destination at night.
He received the weather for the diversion airport and, as he was proceeding to the airport, he received a clearance to descend to 1,600 feet. He began the descent and pulled the power back. When he reached 1,600 feet, he pushed the throttle forward, but the engine did not respond. He then pulled it back towards idle to try and match the throttle to where the engine was operating. The engine surged (went up and back down). He pushed the throttle forward, but there was no response.
He then pitched the airplane to get the speed to about 90 knots (towards best glide). He then declared an emergency and when they were about 100 feet above the trees, he lowered the landing gear. He told the passenger to “Brace” as they were going to crash and transmitted: “Mayday, Mayday, Mayday” before the airplane contacted the trees. He could not remember anything after hitting the trees. The next thing he remembered was being in the hospital.
The pilot reported that he had his lap belt on, but the shoulder harness was broken, and had been that way since when he purchased the airplane. The passenger had her lap belt on, but he could not remember if she had her shoulder harness on. He did not try to check the magnetos or switch tanks after the loss of engine power.
He stated that fuel management was not an issue as he would set the timer on his Garmin unit every 15 minutes, and if the fuel tank he was on was higher than the other one he would stay on that tank. He would determine the quantity by looking at the fuel gauges to estimate what fuel he had. He also stated that he was at the halfway point and should have had enough fuel to make it, or close. He could not remember what tank he was on when the accident occurred. He added that he just wanted to configure the airplane for landing and all he saw was trees. PERSONNEL INFORMATIONAt the time of the accident, the pilot was a colonel in the United States Air Force, was rated as a command pilot, and had flown the T-37A, T-38A, C-130E, AT-38B, F-16C, A-10A, and A-10C.
According to Federal Aviation Administration (FAA) records, the pilot held a commercial pilot certificate, with ratings for airplane single-engine land, airplane multi-engine land, and instrument airplane.
His most recent FAA second-class medical certificate was issued on October 20, 2021. At the time of the accident, he had accrued approximately 1,968 total flight hours, of which about 76 hours were in the accident airplane make and model. AIRCRAFT INFORMATIONMaintenance Records
A review of partial copies of the airplane’s maintenance logbook entries had revealed that the engine had accumulated 2083.76 hours at the time of the most recent annual inspection dated August 5, 2021.
According to maintenance records, the airplane's most recent annual inspection was completed on August 5, 2021. At the time of the inspection, the airplane had accrued about 6,050 total hours of operation, and the engine had accrued about 2,084 hours since major overhaul.”
Fuel System
The fuel system consisted of two interconnected tanks in each wing, having a combined capacity of 49 U.S. gallons, for a total capacity of 98 U.S. gallons (94 usable). Fuel flow was indicated on a gauge located in the instrument panel. A fuel quantity gauge for each wing system was also located in the instrument panel, which indicated the amount of fuel remaining as transmitted by the electric fuel quantity sending units located in the wing tanks. An exterior sight gauge was installed in the inboard tank of each wing so fuel quantities could be checked on the ground during the preflight inspection of the airplane.
Fuel was drawn through a finger screen located in the inboard fuel tank and routed to a three-position fuel selector valve and filter unit which was located aft of the main spar. The valve had “OFF,” “LEFT,” and “RIGHT” positions that were remotely selected by means of a torque tube operated by a handle located in the pedestal. The handle had a spring-loaded detent to prevent accidental selection to the “OFF” position. From the selector valve the fuel would go to the electric fuel pump, which also was mounted aft of the main spar and then would go forward to the engine-driven fuel pump, which forced the fuel through the injector unit into the engine.
Guidance for Fuel Tank Selection
According to the Pilot’s Operating Handbook (POH) for the airplane, to keep the airplane in best lateral trim during cruise flight, the fuel should be used alternately from each tank at one-hour intervals.
The POH also stated, “Always remember that the electric fuel pump should be turned ‘ON’ before switching tanks and should be left on for a short period thereafter. To preclude making a hasty selection, and to provide continuity of flow, the selector should be changed to another tank before fuel is exhausted from the tank in use. The electric fuel pump should be normally ‘OFF’ so that any malfunction of the engine driven fuel pump is immediately apparent.
If signs of fuel starvation should occur at any time during flight, fuel exhaustion should be suspected, at which time the fuel selector should be immediately positioned to a full tank and the electric fuel pump switched to the ‘ON’ position.” METEOROLOGICAL INFORMATIONSynoptic conditions
The National Weather Service Surface Analysis Chart for 1700 for the eastern United States depicted a low-pressure system at 1012 hectopascals over the Virginia and North Carolina border, with a cold front extending southwestward into North and South Carolina, Georgia, and into the Florida panhandle. The front then became a warm front and extended westward along the gulf coast. The accident site was located in the vicinity of the cold front. The station models in the vicinity of the accident site indicated westerly winds of 10 knots, clear to scattered clouds over the area with temperatures in the 80's °F, with dew point temperatures in the 60's °F. No significant weather or obstructions to visibility were identified surrounding the accident site.
Observations
The accident airplane was diverting to Lowcountry Regional Airport (RBW), Walterboro, South Carolina, which listed an elevation of 101 ft msl, with a magnetic variation of 7° W based on the sectional chart for the area. The airport had an Automated Weather Observation System (AWOS), which was not augmented by any human observers. The following conditions were reported at the approximate time of the accident:
Routine weather observation for RBW at 1555 included wind from 280° true at 10 knots gusting to 17 knots, visibility 10 statute mile or more, scattered clouds at 5,000 ft agl, scattered clouds at 7,000 ft, and scattered at 9,500 ft, temperature 30° C (86° F), dew point temperature 20° C (68° F), altimeter setting 29.82 inches of mercury.
Sounding
A High-Resolution Rapid Refresh (HRRR) numerical model data was obtained from the National Oceanic and Atmospheric Administration Oceanic Air Resource Laboratory archive using the closest grid point to the accident site coordinates. The HRRR model data was then plotted on a standard skew T log P diagram using analysis software for 1600 on October 22, 2021. The sounding depicted an elevation of 105 ft over the grid point, with a near surface temperature of 27.2°C (81° F), with a dew point temperature of 16.4°C (61.5° F), a relative humidity of 52%, with a density altitude of 1,756 ft. The lifted condensation level was identified at 4,490 ft agl, the level of free convection at 4,490 ft agl, and the convective condensation level at 6,407 ft agl. The freezing level was identified at 13,112 ft which was above the accident airplane’s cruising level at 6,000 ft. The precipitable water content was 1.09 inches. The atmosphere was characterized as conditional unstable with a Lifted Index of -2.9. At 6,000 ft the sounding depicted a temperature of 12° C, a dew point temperature of 1.4° C, with a relative humidity of 45%, with the wind from 260° at 22 knots. The HRRR wind profile indicated the mean 0 to 6 kilometer (or 18,000 ft) wind was from 255° at 25 knots.
During the portion of the flight when the accident airplane’s enroute cruise was at 6,000 feet the winds were from 260° at 21 knots with a temperature of 12° C. AIRPORT INFORMATIONMaintenance Records
A review of partial copies of the airplane’s maintenance logbook entries had revealed that the engine had accumulated 2083.76 hours at the time of the most recent annual inspection dated August 5, 2021.
According to maintenance records, the airplane's most recent annual inspection was completed on August 5, 2021. At the time of the inspection, the airplane had accrued about 6,050 total hours of operation, and the engine had accrued about 2,084 hours since major overhaul.”
Fuel System
The fuel system consisted of two interconnected tanks in each wing, having a combined capacity of 49 U.S. gallons, for a total capacity of 98 U.S. gallons (94 usable). Fuel flow was indicated on a gauge located in the instrument panel. A fuel quantity gauge for each wing system was also located in the instrument panel, which indicated the amount of fuel remaining as transmitted by the electric fuel quantity sending units located in the wing tanks. An exterior sight gauge was installed in the inboard tank of each wing so fuel quantities could be checked on the ground during the preflight inspection of the airplane.
Fuel was drawn through a finger screen located in the inboard fuel tank and routed to a three-position fuel selector valve and filter unit which was located aft of the main spar. The valve had “OFF,” “LEFT,” and “RIGHT” positions that were remotely selected by means of a torque tube operated by a handle located in the pedestal. The handle had a spring-loaded detent to prevent accidental selection to the “OFF” position. From the selector valve the fuel would go to the electric fuel pump, which also was mounted aft of the main spar and then would go forward to the engine-driven fuel pump, which forced the fuel through the injector unit into the engine.
Guidance for Fuel Tank Selection
According to the Pilot’s Operating Handbook (POH) for the airplane, to keep the airplane in best lateral trim during cruise flight, the fuel should be used alternately from each tank at one-hour intervals.
The POH also stated, “Always remember that the electric fuel pump should be turned ‘ON’ before switching tanks and should be left on for a short period thereafter. To preclude making a hasty selection, and to provide continuity of flow, the selector should be changed to another tank before fuel is exhausted from the tank in use. The electric fuel pump should be normally ‘OFF’ so that any malfunction of the engine driven fuel pump is immediately apparent.
If signs of fuel starvation should occur at any time during flight, fuel exhaustion should be suspected, at which time the fuel selector should be immediately positioned to a full tank and the electric fuel pump switched to the ‘ON’ position.” WRECKAGE AND IMPACT INFORMATIONExamination of the accident site revealed that the airplane first contacted an approximately 70-foot-tall pine tree, and then continued to travel through about 100 yards of forest on a magnetic heading of about 072°, striking multiple trees while descending on an approximate 20° flight path angle.
The postaccident examination of the airplane revealed that both wings and the right side of the stabilator had separated from their mounting locations during the impact sequence with the trees. There was no evidence of pre-impact fire, and all impact damage was consistent with tree and terrain impact.
The fuselage was mostly consumed by a postimpact fire. Examination of the burn pattern indicated that the postimpact fire appeared to initiate from the area of the right wing. Residual fuel was found in the right outboard fuel tank. Fuel staining was also present around the fuel filler port for the right wing. Minimal thermal damage on the inboard leading edge of the left wing was present, but residual fuel, and fuel staining, were not evident.
The landing gear was in the down position, and the landing gear dump lever was stowed. The throttle, propeller, and mixture were all in the full forward position. The fuel selector valve was in the right fuel tank position. Flight control continuity was established from the cockpit controls to the breaks in the system and from the breaks in the system to the control surfaces. The wing flaps were in the up (0°) position. The left wing outboard and inboard fuel tanks were breached. There was no evidence of vegetation blight nor residual odor of fuel in the vicinity of the wing. The right-wing outboard fuel tank was breached (but still contained residual fuel), and the right inboard fuel tank had separated from the wing. Both the left and right fuel filler caps were still attached to their receptacles. About 1.5” of pitch trim jack screw threads were exposed from the top of the trim barrel assembly, which was indicative of a “near full nose up” stabilator trim setting.
The postaccident examination of the aluminum 3-bladed constant-speed propeller and spinner revealed that the propeller had remained attached to the propeller flange, and no rotational deformation was present on the impact damaged spinner. Impact damage was noted to the propeller hub and all three blades. There was no leading-edge damage or chord-wise abrasions noted on the propeller blades.
The postaccident examination of the engine revealed that the engine had remained attached to its mount which had partially separated from the fuselage. Both the engine and its mount exhibited impact and thermal damage. The exhaust system was impact damaged but remained attached to its respective cylinder attach points. No internal obstructions or deformations were noted in the exhaust system. The single drive, dual magneto installation, and the engine-driven fuel pump were thermally destroyed. The spark plugs exhibited dark gray, sooty coloration, and worn normal condition. The Nos.3 top, 5 top, 1 bottom, 2 bottom, 3 bottom and 5 bottom spark plugs were oil soaked, consistent with how the engine came to rest.
Thumb compression and suction were obtained, and crankshaft and camshaft continuity to the rear gears was established. The interiors of the cylinders were observed with a lighted borescope and no anomalies were observed. Oil was observed within the sump; the oil pump suction screen was clear of debris, and the oil filter media was charred. No metallic debris was observed between the folds of the media. One tooth was found to be fractured on the oil pump drive gear, and its driving idler gear exhibited abrasions on several consecutive teeth. The fractured gear tooth was retrieved from the oil sump. The oil pump could not be rotated by hand.
Examination of the oil pump by the NTSB Materials Laboratory indicated that the drive gear failed from a tooth that fractured in overstress while engaged with the adjacent idler gear. The directions of the fracture surface features and adjacent damage to the drive gear and idler gear, suggested the forces were in the direction of rotation and were consistent with the failure occurring during the impact sequence.
The examination of the engine fuel system revealed that the fuel injector servo remained attached to the engine and exhibited soot and discoloration consistent with exposure from the postimpact fire. The throttle cable rod end remained attached to the servo throttle arm. The arm was positioned at the full throttle position. The mixture cable rod end remained attached to the servo mixture control arm. The arm was positioned at a mid-range position. The mixture control stop screw was not observed. The servo fuel regulator section was partially disassembled; the hub stud was still in place, and the rubber diaphragms were destroyed by fire. The fuel screen was clean.
The fuel flow divider remained attached to the engine and exhibited soot and discoloration consistent with exposure to the post-impact fire. The fuel injector lines were secure. The flow divider was partially disassembled, and no evidence of fuel was found in the flow divider. The rubber diaphragm was destroyed by fire.
The fuel injector nozzles remained attached to the engine and the fuel lines were secure. All six nozzles were found to be unobstructed. ADDITIONAL INFORMATIONFuel Consumption
A review of automatic dependent surveillance - broadcast (ADS-B) data and ATC information from the accident flight indicated that the pilot had made multiple changes in altitude during the flight. He initially climbed to 6,000 feet msl and entered cruise. He then climbed to 10,000 feet and entered cruise. He then descended to 8,000 feet and entered cruise. He then descended to 6,000 feet and entered cruise, and then descended to 4,000 feet and entered cruise, before climbing back up to 6,000 feet and entered cruise. He then descended to 1,600 feet and entered cruise before the loss of engine power occurred, and the airplane descended to impact.
Further review indicated that the accident flight took about 3 hours, during which the airplane flew about 351 nautical miles, at an average ground speed of 116 knots.
Fuel Consumption Calculations
At the request of the NTSB, Piper Aircraft’s Flight Operations Department was asked to review the accident flight and determine possible fuel consumption.
During the review, it was assumed that when the airplane was climbing, the power was set to the maximum continuous power available. In cruising flight, it was assumed that the power setting was constant while the airplane was maintaining altitude. When the airplane was descending, it was assumed that the power was not reduced as the average ground speed increased significantly during the descent.
The review showed that had the pilot operated the engine at 75% power during cruise flight, with the fuel air mixture leaned for best performance, the engine would have consumed about 56.7 gallons during the flight. With the fuel air mixture leaned for best economy, the engine would have consumed about 51.5 gallons during the flight.
Had the pilot operated the engine at 55% power during cruise flight, with the fuel air mixture leaned for best performance, the engine would have consumed about 47.7 gallons during the flight. With the fuel air mixture leaned for best economy, the engine would have consumed about 41.8 gallons during the flight
Pilot’s Handbook of Aeronautical Knowledge
According to the Pilot’s Handbook of Aeronautical Knowledge (FAA-H-8083-25C), the fuel quantity gauges indicate the amount of fuel measured by a sensing unit in each fuel tank and is displayed in gallons or pounds. Aircraft certification rules require accuracy in fuel gauges only when they read “empty.” Any reading other than “empty” should be verified. Do not depend solely on the accuracy of the fuel quantity gauges. Always visually check the fuel level in each tank during the preflight inspection, and then compare it with the corresponding fuel quantity indication.
It goes on to say in part that, regardless of the type of fuel selector in use, fuel consumption should be monitored closely to ensure that a tank does not run completely out of fuel. Running a fuel tank dry does not only cause the engine to stop, but running for prolonged periods on one tank causes an unbalanced fuel load between tanks. Running a tank completely dry may allow air to enter the fuel system and cause vapor lock, which makes it difficult to restart the engine. On fuel-injected engines, the fuel becomes so hot it vaporizes in the fuel line, not allowing fuel to reach the cylinders.
Civil Air Regulations (CARs)
Prior to 14 CFR Part 23, which addresses airworthiness standards for normal category airplanes, the CARs were the basis for establishing the design requirements for aircraft. Eventually CAR 3, which addressed airplane airworthiness for normal, utility, acrobatic, and restricted purpose categories, grew to become the regulatory guidance specific to small airplanes.
The requirements for fuel quantity indicators at the time were for the indicator to be calibrated to read zero during level flight when the quantity of fuel remaining in the tank was equal to the unusable fuel supply.
The airplane design was originally certificated under these regulations.