Montgomery, TX, USA
N141SW
Beech A45
While maneuvering during an upset recovery training flight, the left wing separated from the airframe, which resulted in an uncontrolled descent and impact with terrain. A review of an on-board video revealed the instructor and student were performing training maneuvers which included steep turns, stalls, accelerated stalls, unusual attitudes and recoveries from these to a wings level attitude using several techniques. During the final maneuver, the instructor asked the student to lower the nose to "about a hundred and forty knots", and afterwards told the student to slowly pitch the nose upward "until we're pointed straight up." The airplane was seen climbing vertically up and visual contact with the ground disappeared. The instructor then told the student to "pull the way we just did a minute ago and pull the airplane into a stall." A brief stall occurred, and then the airplane continued to pitch in the same direction, and its path resembled the remainder of an inside loop. As the ground reappeared into the view, the aircraft was inverted and descending. There was a slight roll to the left as the airplane was descending while its pitch attitude continued in the same trend toward a vertical nose down attitude. While in a steep nose down attitude (no sky visible in the view), the instructor told the student to "pull it into a stall right now." At that moment, the recording ended. The main wreckage came to rest on the side of a hard surface gravel road, and the left wing, left horizontal stabilizer, inboard section of left elevator, aft canopy frame, and a portion of the left wing skin were located in a wooded area approximately 0.4 miles southwest of the main wreckage. The true history of the airframe could not be substantiated. All applicable Federal Aviation Administration Airworthiness Directives had been complied with at the time of the accident. Examination of the wing and carry-through structure revealed the structure failed as the result of extensive and widespread fatigue cracking in the -31 and -33 channels and the -3 and -85 webs. The cracks in the channels were in hidden areas and probably could not have been directly detected without extensive disassembly of the structure. However, the cracks in the webs would have been easily detected, and the crack in the forward web apparently was detected, based on the stop-drilled hole and the notes in the maintenance records. The materials of the structure were in compliance with required specifications. However, the workmanship was poor as indicated by the trapped debris and damaged holes. This may have been acceptable standards of workmanship at the time of manufacture, but have since been recognized as having a large negative impact on fatigue life of the structures. The fractured hole in the rear spar was recently inspected with no indication of cracks. It is highly unlikely that the cracks initiated and grew to the current sizes in less than 40 hours of flight time since the inspection. The localized damage and enlargement of the hole could have reduced the effectiveness of the inspection. The fatigue cracking in the carry-through, the rear wing spar, and the horizontal stabilizer indicate that the fatigue life of the entire aircraft structure has been expended. It is strongly suspected that these conditions may exist in other T-34 airframes.
HISTORY OF FLIGHT On December 7, 2004, at 1020 central standard time, a Beech A45 single-engine airplane, N141SW, registered to PRVNY PLUK, LLC, of Houston, Texas, and operated by Texas Air Aces Inc., d.b.a. Aviation Safety Training, of Spring, Texas, was destroyed when it impacted terrain following an in-flight separation of the left wing and subsequent loss of control near Montgomery, Texas. The airline transport pilot (pilot-in-command/safety pilot) and pilot-rated passenger (client) were both fatally injured. Visual metrological conditions prevailed, and no flight plan was filed for the 14 Code of Federal Regulations Part 91 demonstration flight. The flight originated from the David Wayne Hooks Municipal Airport (DWH), near Houston, Texas, approximately 0945. The client attended Aviation Safety Training for a two-day Advanced Maneuvering Program (AMP). The program included ground school and flight training that focused on unusual attitudes and upset recovery. The client completed the ground school portion of the training the day prior to the accident. The accident flight was the first of two flights for the flight portion of the program. The accident flight was a single aircraft flight; according to the operator, typically the AMP training consisted of two aircraft training simultaneously in the practice area. The airplane was equipped with an on-board video/audio recording system. According to the operator, the videotapes are used for the purpose of post-flight debriefings. A review of the videotape revealed the video view was from a tail-mounted camera, which looked forward toward the canopy, and the view extended laterally to both wingtips. The camera view remained the same throughout the recording. The recording contained approximately 35:27 (minutes:seconds) of continuously recorded video and audio. All times of the recording in the History of Flight section of the factual report are elapsed times from the beginning of the recording unless otherwise specified. The elapsed time format is in hours, minutes, and seconds (HHMM:SS). The recording began with the airplane on the ground at DWH in a parking area with the engine running. The safety pilot, seated in the rear seat, requested and received clearance and taxi instructions to runway 35L. The airplane approached the departure end of the runway, stopped on the taxiway, and the safety pilot performed pre-flight run-up procedures. After a position and hold clearance, the airplane was cleared for takeoff and began the takeoff roll. Shortly after the takeoff roll began, the safety pilot gave control of the airplane to the client, informed him that the takeoff would be his, and the safety pilot would maintain control of the engine power. The airplane took off and generally maintained runway heading for the next 12 minutes of video. The airplane climbed in steps; first to 2,800 feet and then to 3,800 feet in order to remain clear of Class B airspace. Approximately 0015:00, the airplane reached the vicinity of Lake Conroe at 3,800 feet. At 0016:17, a climb to 6,000 feet was initiated. After reaching 6,000 feet, the safety pilot and client began performing the AMP training maneuvers. The safety pilot described each maneuver beforehand, as well as during each maneuver. The training maneuvers included steep turns, stalls, accelerated stalls, unusual attitudes and recoveries from these to a wings level attitude using several techniques. The maneuvers performed demonstrated the airplane's response to 'rudder only' recovery techniques at low and high angles of attack, 'rudder combined with aileron' recoveries also at low and high angles of attack, and demonstrations of positive dynamic and static stability of the airplane. At 0034:50, the safety pilot asked the client to lower the nose to "about a hundred and forty knots," and afterwards told the client to slowly pitch the nose upward "until we're pointed straight up." The airplane was seen climbing vertically up and visual contact with the ground disappeared. The safety pilot then told the client to "pull the way we just did a minute ago and pull the airplane into a stall." A brief stall occurred, and then the airplane continued to pitch in the same direction, and its path resembled the remainder of an inside loop. As the ground reappeared into the view, the aircraft was inverted and descending. There was a slight roll to the left as the airplane was descending while its pitch attitude continued in the same trend toward a vertical nose down attitude. While in a steep nose down attitude (no sky visible in the view), the safety pilot told the client to "pull it into a stall right now." At that moment (0035:26), the recording appeared to end. According to witness statements, at the time of the accident, the witnesses were working approximately 1/2 mile from the accident site. Witnesses heard a "bang" and noticed an airplane in a near vertical attitude. The witnesses then observed a wing and several other small components separate from the airplane. After the wing separation, the airplane spiraled nose down toward the ground. Subsequently, the airplane impacted a hard surface gravel road. The witnesses secured the area until the local authorities arrived. PERSONNEL INFORMATION The pilot-in-command, designated as the safety pilot, occupied the rear seat. The pilot held an airline transport pilot certificate with an airplane multi-engine land rating. The pilot also held a commercial pilot certificate with an airplane single-engine land rating. The pilot was issued a second-class medical certificate on October 4, 2004, with a limitation for corrective lenses. According to the pilot's insurance records dated November 16, 2004, the pilot had accumulated 5,280 total flight hours and 792 total hours in the make and model of the accident airplane, of which 20 hours were in the previous 90 days. The records revealed the pilot was an ex-military fighter pilot. According to the operator, the pilot had been employed with them since October 2001, and had been the operator's chief pilot since December 2003. The pilot-rated passenger, designated as the client, occupied the front seat. The pilot held an airline transport pilot certificate with an airplane multi-engine land rating. The pilot also held a commercial pilot certificate with an airplane single-engine land rating. The pilot was issued a first-class medical certificate on October 24, 2004, with no restrictions or limitations. According to an October 2003 medical certificate application, the pilot reported a total of 14,700 hours. AIRCRAFT INFORMATION The A-45 (military designation T-34A, B45) airplane is a single-engine, tandem-seat trainer manufactured by Beech Aircraft Corporation. The airplane was designed to meet the requirements of a primary military trainer and, at the same time, prepare the student pilot for the transition to heavier, higher-performance airplanes. The overall dimensions of the airplane are a wingspan of 32.8 feet, a length of 25.9 feet and a height of 9.6 feet. The normal gross weight of the airplane is 2,950 pounds. The airplane utilizes three landing gear in a retractable tricycle configuration. The entire T-34 A and B production was sold to U.S. military customers or exported to foreign military customers. The airplane was delivered with a Continental O-470-13 engine rated at 225 horsepower. The accident airplane had a Continental IO-550-B9F engine rated at 300 horsepower. According to Federal Aviation Administration (FAA) registration records, the accident airplane was loaned to the Dyes Air Force Base (AFB), Texas, Aero Club on September 29, 1958, at a reported time of 1,901.09 hours. On October 15, 1958, the airplane was issued a FAA Standard Airworthiness Certificate and entered civilian use as a Dyes AFB Aero Club asset. It was released from the United States Air Force (USAF) in January 1965 and was transferred to the Civil Air Patrol. The certificate of ownership (dated February 25, 1965) at the time of transfer lists the USAF Serial Number as 53-4113 with no Manufacturer Serial Number (S/N) listed. According to FAA Aircraft Specification No. 5A3, T-34A, USAF S/N 53-4113, was manufactured by the Canadian Car and Foundry Company as manufacturer's S/N 34-82. The Federal Aviation Agency (precursor to the FAA) Application for Aircraft Registration, also dated February 25, 1965, lists the S/N as 53-4113 with a hand written notation "G-13" above the type written number. According to Raytheon records, airplane S/N G-13 was manufactured as USAF S/N 52-7632A. In a June 1965 letter from Dyes AFB to the FAA, the USAF reported that airplane USAF S/N 52-7632A, N7830B, had crashed in July 1959 and was "turned over to salvage for reclamation and disposition." The Civil Air Patrol sold the airplane to a private individual in January 1972 as S/N G 13AF53 4113A. It was sold once more with this serial number before being sold in July 1974 as S/N G-13. In October and again in December 1977, the airplane was sold as S/N 6-13AF53-4113 and in February 1978 as S/N 53-4113A. The records indicate that the N-number was changed from N7979A to N20M in February 1978. On November 13, 1981, N20M was involved in an accident in which the airplane received substantial damage (See NTSB accident CHI82FEM02). The Deregistration of United States Civil Aircraft form lists airplane S/N G-13 as "totally destroyed or scrapped" on September 28, 1982. Prior to the airplane being deregistered, in March 1982, the airplane was again sold, this time as S/N G-13. From this point on, the airplane was sold five times as S/N G-13. The records indicate that on May 12, 1990, the airplane was ditched at sea by the owner. The insurance company recovered the airplane and treated it as a total loss. The Deregistration of United States Civil Aircraft form lists airplane S/N G-13 as "totally destroyed or scrapped" on June 26, 1990. Subsequently, in July 1990, the airplane was sold to Nogle & Black Aviation. According to Nogle & Black, the data plate was removed from the ditched hull (S/N G-13) and it and the airworthiness certificate were used to build a new airplane with new surplus and/or used serviceable parts. On February 1, 1991, a FAA Standard Airworthiness Certificate was issued to an airplane identified as registration N141SW and S/N G-13. This airplane was sold to Sky Warriors in December 1990 and then to PRVNY PLUK, LLC in April 2003. This accident was the third fatal wing separation on a T-34 airplane during civilian operation. In April 1999, a Beech T-34A, N140SW, collided with the ground following the in-flight separation of the right wing near Rydal, Georgia (see NTSB accident ATL99FA072) during a laser combat simulation (dogfight) flight conducted by Sky Warriors. In November 2003, a Beech T-34A, N44KK, impacted the ground following the in-flight separation of the right wing near Montgomery, Texas (see NTSB accident FTW04FA025) during a simulated air combat demonstration conducted at the end of an AMP training flight by Texas Air Aces. The current accident airplane, N141SW, was the 'adversary' airplane in both of the previous accidents. In August 2001, in response to the 1999 accident, the FAA issued Airworthiness Directive (AD) 2001-13-18, which limited the flight envelope of all T-34 airplanes until they had performed a detailed inspection of the wing spars in accordance with Raytheon Service Bulletin (SB) 57-3329. The FAA also approved four Alternate Means of Compliance (AMOC) to the AD. As a result of the November 2003 accident, the FAA revised AD 2001-13-18 because they "determined that those AMOCs do not address all critical areas in the wing spar assemblies and should no longer be valid." AD 2001-13-18R1 became effective on March 15, 2004 and eliminated the AMOC approvals thus requiring the T-34 owners perform the Raytheon SB inspections. Subsequent to the revised AD, the four original AMOC holders developed additional inspections to provide an equivalent level of safety in order to get all four AMOCs re-approved for compliance with AD 2001-13-18R1. A review of the airframe logbook revealed the accident airplane complied with AD 2001-13-18R1 through the use of an AMOC on August 3, 2004. In November 1962, the FAA issued AD 62-24-01, which requires that both horizontal stabilizers be removed from the airplane and inspected for cracks on the front and rear spars between the butt rib and the inboard end using the dye penetrant method. The inspection is to be repeated every 500 hours. According to the logbook, this inspection was last completed on January 4, 1999, at an airplane total time of 9035.5 hours. All other applicable Airworthiness Directives had been complied with according to the logbook. The airframe logbook supplied to the investigation began on December 24, 1990, with a total airplane time of 4947.5 hours and a Hobbs time of 0 hours. The 4,947.5 hours of total airplane time could not be substantiated. The installation of a new Hobbs meter reading 0 hours was substantiated. The first entry details major maintenance on the airplane including the installation of a new engine and the gun camera system that occurred after the airplane was ditched. Between the November 2003 accident and August 3, 2004, the airplane was operated for 0.2 hours. After August 3, 2004, it was operated for 36.2 hours prior to the accident. At the time of the accident, the airplane had accumulated 9316.3 hours (total airframe time). According to the logbook, on August 3, 2004, the airplane underwent an annual inspection, a 100-hour inspection and major maintenance that included replacing the elevators and overhauling the propeller and governor. The entry in the logbook also states "Doublers were installed on the front carry through structure bulkhead web in accordance with T-34 structural repair manual figures B24 and B25, by Vern Gibson. Found installation to be acceptable." According to Vern Gibson, he discovered the cracking on the carry through web, stop drilled the cracks, installed the doublers in accordance with the figures, and repainted the area with zinc chromate. The referenced figures are from the Structural Repair Instructions for the Navy Model T-34B Aircraft, NAVAIR 01-90KDB-503. Examination of the wreckage revealed that the splice plates in Figure B25 were not installed on the accident airplane. The figures do not appear in the Beechcraft Mentor, Model B-45, Structural Repair Manual and are not FAA approved or accepted data. As part of the AMOC compliance with the AD, the lower, rear bathtub fittings and the two fastener holes in the right and left aft trunnion fittings were inspected for cracks with no faults found. The collection of FAA Form 337, Major Repairs and Alterations, were reviewed. In February 1985 the airplane was "repaired following accident." During this repair, both wing spars were replaced, the left leading edge was replaced, both wings, ailerons and flaps were re-skinned, the forward fuselage was rebuilt, and the elevators, horizontal stabilizers, and vertical stabilizer were re-skinned. No record of the mentioned accident could be located in the NTSB or FAA databases. In April 1987, the airplane was repaired due to a nose landing gear collapse. The lower, forward area of the airplane was rebuilt, the propeller was overhauled and the nose landing gear doors were replaced. There are two 337s from January 1991 that list the installation of a new engine and the installation of the gun camera system. There is also a detailed work order and bill from Nogle & Black Aviation that includes the engine and gun camera installations along with a rebuild of the entire airplane. This date corresponds to the time when the airplane was rebuilt following the ditching. In June 1996, both wing forward spars were replaced with used serviceable spars and the box sections were repaired. In March 1997, the right wing top skin was replaced, the rear spar was repaired and the flap and aileron were re-skinned. The rudder was reworked in August 2003 and both elevators were reworked in April 2004. METEOROLOGICAL INFORMATION At 0953, the Montgomery County Airport
the in-flight separation of the left wing as a result of extensive fatigue cracking throughout the wing carry-through structure.
Source: NTSB Aviation Accident Database
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