Suffolk, VA, USA
N230BW
TEAM ROCKET F-1 F-1
The pilot and pilot-rated passenger were performing aerobatic maneuvers in the experimental amateur-built airplane. After the pilot had performed several aileron rolls, barrel rolls, and wing overs, the pilot-rated passenger in the aft seat attempted to conduct a barrel roll. Data from onboard avionics indicated that, during the descending portion of the roll, the airplane reached a 9,166 ft-per-minute rate of descent at an airspeed of 238 knots, 2 knots below the airplane’s never-exceed speed (Vne). The pilots then heard a loud noise and felt a buffet in the aft flight controls, and reported limited pitch control movement. The airplane subsequently experienced a negative G-load and an decrease in pitch attitude. The pilot attempted to recover from this rapid descent, during which the airplane reached an airspeed of 240.5 knots and a +3.68g-load. The pilot was able to recover at 455 ft mean sea level and return to the airport and land. Postaccident examination of the airplane revealed that the right horizontal stabilizer forward of the aft spar was missing and the elevator assembly remained attached. The left horizontal stabilizer and associated elevator assembly was bent downward but remained attached and operable. The upper and lower straps on the forward spar only had four rivets each including the one at the closeout rib, but, according to kit manufacturer’s specifications, there should have been five rivets each. This likely lowered the structural integrity of the stabilizer and contributed to the structural failure but was likely not the primary cause. Although flutter was reported by both pilots and could not be ruled out, the damage to the horizontal stabilizer was consistent with its failure due to aerodynamic overload during aerobatic maneuvers near the airplane’s Vne.
On December 24, 2019, about 1415 eastern standard time, an experimental amateur-built F-1 Rocket, N230BW, was substantially damaged when it was involved in an accident near Suffolk, Virginia. The airline transport pilot and private-pilot-rated passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot, who owned the airplane and was pilot-in-command for the flight, was seated in the front seat and the pilot-rated passenger was seated in the aft seat. The pilot reported that, after performing several touch-and-go landings, they flew southeast of the airport and conducted several aileron rolls, barrel rolls, and wing-overs at airspeeds between 150 knots (kts) and 180 kts and no more than +3g, which was below the airplane’s limit of +6g. Additionally, he stated that momentary speeds of 225 kts were witnessed during two nose-high pulls into wing overs. The pilot stated that he believed he was flying well within the aerobatic specifications of the aircraft, which he believed were +6/-3g at 2,000 lbs. At the conclusion of the sequence, the pilot-rated passenger took the controls and executed two aileron rolls followed by two barrel rolls. He initiated the second barrel roll about 3,000 ft mean sea level (msl) at 165 kts and then climbed to about 4,000 ft msl. The passenger entered the airplane into a 25° nose-down pitch attitude, and as the airspeed increased above 180 kts, he pulled back on the stick to recover from the descent. During the recovery, the pilots heard a loud noise and felt a buffet. All engine parameters appeared normal, but a “flutter” was felt in the airframe and the controls had limited movement. A couple of seconds later, there was a negative G nose-over and both pilots hit their heads on the canopy. The pilot took control of the airplane, reduced engine power to idle, and recovered. The pilot reported that he had difficulty with pitch control during the flight to Virginia Hampton Roads Executive Airport (PVG) Norfolk, Virginia. During the first landing attempt, the airplane porpoised several times, so the pilot initiated a go-around, then made a successful landing during his second attempt. The airplane was equipped with a Dynon Avionics (D-180) unit. Data downloaded from the unit revealed that, during the second barrel roll maneuver and just before the pilot’s report of a flight control problem, the airplane was flying about 2,422 ft mean sea level (msl) at a negative 22.87° pitch and a vertical speed of 9,166 ft per minute (fpm) at an airspeed of 238 kts (2 kts below the never-exceed speed [Vne]). Several seconds later, the g-loading went from +1.25 to -2.31 and the pitch increased to -38° degrees. The airspeed increased to over 240 kts as the airplane descended at 10,921 fpm with a corresponding load of +3.68g. While in the dive, the airspeed continued to increase to 244 kts and remained over 240 kts for 6 seconds. The pilot recovered from the dive at 455 ft msl and initiated a positive rate of climb. The pilot reported light turbulence in the area at the time of the accident and wind from 220° at 15 kts. Reported weather conditions at SFQ, located about 5 miles from the accident location, included wind from 040° at 9 kts. Reported weather conditions at Chesapeake Regional Airport (CPK), Norfolk, Virginia, located about 10 miles east, included wind from 010° at 11 knots with gusts to 16 kts. The reported weather conditions at PVG, about 10 miles north of the accident location included wind at 10 knots gusting to 18 knots. A postaccident examination of the airplane by a Federal Aviation Administration inspector revealed that the right horizontal stabilizer structure, forward of the aft spar and outboard of the fuselage, was missing. A subsequent examination was conducted by a third party consisting of two airframe and powerplant mechanics and an engineer, all of whom had extensive experience in the airframe design. At the forward spar attachment location, eight rivets (four upper and four lower) that had attached the forward spar to the upper and lower straps were fractured, and the outboard end of the upper strap was bent downward. The aft spar was twisted counterclockwise (as viewed looking outboard) and bent downward. The aft spar upper flange was cracked at the inboard closeout rib location, and the lower half of the spar was buckled and cracked just outboard of the fuselage. Rivets attaching the upper skin to the aft spar were fractured or pulled out along the aft spar’s upper flange. The left horizontal stabilizer and associated elevator assembly was bent downward but remained attached and operable. The inboard closeout rib was deformed and cracked at the upper forward end of the rib. The upper and lower straps on the forward spar only had four rivets each, including the one at the closeout rib; according to kit manufacturer’s specifications, there should be five rivets: four outboard of the rib and one inboard (see figure). Figure. Photo showing missing rivets in spar cap. The airframe of the F-1 Rocket utilized an empennage identical to the Van’s RV-7. In 2014, Van’s issued Service Bulletin 14-01-31 to address potential cracking of the front horizontal stabilizer spar. No visual evidence of prior/pre-accident cracking on the accident airplane was discovered.
A structural failure of the horizontal stabilizer during aerobatic maneuvers near the airplane’s never-exceed speed. Contributing to the failure was the construction of the horizontal stabilizer that did not meet the kit manufacturer’s specifications.
Source: NTSB Aviation Accident Database
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