Introduction
On June 7, 2018, about 1024 central daylight time, a Beech F33A airplane, registration N3291X, experienced a total loss of engine power while in flight, leading to a forced landing near Annandale Ranch Airport (2XS7) in Uvalde, Texas. The pilot sustained serious injuries, and the airplane was destroyed by a post-impact fire. The aircraft was registered to a private individual and operated under Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan had been filed.
Flight History
The flight departed from Live Oak County Airport (8T6) in George West, Texas, about 0930, en route to Sierra Blanca Regional Airport (SRR) in Ruidoso, New Mexico. The airplane's annual inspection had been completed on June 5, 2018, at a maintenance facility at Card Airfield (4XA2) in Kenedy, Texas. The pilot reported that he flew the airplane from 4XA2 back to his home base at 8T6 on June 6, a distance of 31 nautical miles. On the morning of the accident, the pilot topped off the fuel tanks before departing.
While en route, the weather was clear. The pilot received a transponder code for visual flight rules (VFR) flight following from air traffic control (ATC) and was cleared through 8,500 ft mean sea level. According to the pilot, the manifold pressure suddenly dropped with a simultaneous engine explosion. The engine access doors blew open, oil spewed onto the windshield, and fire appeared. The pilot reduced the mixture, throttle, and propeller controls. After reporting the emergency to ATC, they provided vectors to the nearest airstrip, 2XS7. The pilot noted difficulty maintaining glide speed due to the nose pitching upward, requiring him to hold the yoke forward firmly. During the descent, he extended the landing gear. A second explosion occurred when the airplane struck trees and rocks. The airplane became engulfed in flames, and the pilot removed his seatbelt and egressed. He was airlifted to a local hospital and treated for second- and third-degree burns.
ATC data showed the airplane's flight track beginning at 0937 about 5 nautical miles northwest of 8T6. The airplane was in cruise flight at approximately 8,500 ft msl and about 110 nautical miles from 8T6 when the emergency was declared. At 1018, the airplane made a left descending turn toward 2XS7. The final radar return at 1023 showed the airplane at about 2,300 ft msl (1,000 ft above ground level) on a heading of 99°.
Wreckage and Examination
The responding FAA inspector found the airplane among trees on the west side of 2XS7, about 500 yards from the threshold of runway 8. The post-impact fire consumed the majority of the airplane. The wreckage debris path began with the left horizontal stabilizer and elevator being sheared off, followed by the left wing, left wing tip fuel tank, and nosewheel. The right wing, right wing tip fuel tank, fuselage, main landing gear, and engine/engine compartment remained together at the final resting position. The fuel tanks were breached, and there was evidence of a large fire around the airplane.
Examination of the wreckage revealed significant fire damage to the rear of the engine compartment at the engine accessory area. A thick white/grey powdery ash covered the damaged accessory area, and an estimated 8-inch hole was found in the crankcase under the left magneto. There appeared to be little to no oil inside the engine and very little oil around the outside of the hole. The top front section of the engine remained mostly free of damage and ash. The exhaust tubing and routing for the turbo-normalizing system showed no damage or apparent anomalies. Visual examination of the oil tubing, oil filter, and oil cooler revealed that some components had been consumed by fire. The oil filter was loose on its mount; it rotated about one-half of a full turn clockwise until safety wire restricted further rotation, then rotated back counterclockwise to the original position. The oil filter was not completely tightened, but the reason for the additional rotation space was not determined. The oil filter gasket had been consumed by fire, and the exhaust manifold directly below the oil filter and oil cooler exhibited burn marks.
The wreckage was recovered to a secure storage facility, where it was examined by the investigative team under the supervision of the NTSB investigator-in-charge. The forward fuselage, firewall, engine, and propeller were complete in one piece. The fuselage was mostly consumed by fire, and the wings were impact damaged and partially consumed. Flight control cables exhibited overload separations in multiple locations. The rear of the engine and firewall sustained thermal damage but remained mostly intact. The cylinders remained attached to the crankcase, and the No. 2 connecting rod was loose inside the large hole in the case. The engine was equipped with a turbo-normalizing system per supplemental type certificate STC SE5222NM. The oil lines to and from the turbo controller remained intact, but the controller was separated from its mount.
The engine was removed from the firewall for a full tear-down at the manufacturer's facility. The left magneto was broken from its mount, and a hole was found in the crankcase above the number two cylinder. The number two connecting rod had separated from the crankshaft, with some of the rod still attached to the No. 2 piston pin and found in the No. 2 cylinder. The Nos. 3 and 4 connecting rods exhibited thermal damage consistent with a lack of oil lubrication. All oil passages in the crankshaft and crankcase were clear of any blockages. The No. 2 rod journal was thermally damaged, and the oil passage was melted and smeared closed due to excessive heat. Excluding the mechanical damage from the internal engine components and the post-crash fire, the remainder of the engine exhibited normal operating signatures and no additional anomalies were noted.