Safety Accident Analysis
Risky intent?
M
any pilots are quick to lambast our various certifying organisations as being overly proscriptive, bureaucratic and even, in some instances, ‘killjoys’. Many pilots fly homebuilt aircraft considered ‘experimental’, and surely the principal is in the title – ‘... it’s experimental guys, which means we can give it a go’. I must confess to thinking like this at times in my own flying career – and during a recent aircraft build – but it is for the better that we have that independent oversight. As these two accidents show, when left to our own devices, it might be good to have someone point a finger and ask ‘are you sure about that?’
Accident 1
An experimental amateur-built Jet Eze aeroplane was destroyed after an inflight break-up and a subsequent impact with terrain near Covington Municipal Airport, Tennessee. The owner, an airline transport pilot, was fatally injured. According to a witness, who routinely observed the accident aeroplane’s flights and was familiar with the aeroplane’s design, reported that the aeroplane departed and climbed to an altitude of about 1,000ft before starting a 270° descending right turn to overfly the airfield at about 200ft, with an estimated speed of 200kt to 210kt. Shortly after the aeroplane crossed the runway, he saw the left wing and winglet ‘oscillate’ about five times, and that the left wing then ‘exploded’. This witness subsequently observed pieces of
the aeroplane falling, abruptly pitching up about 90°, the right wing separating from the fuselage – and then the aeroplane descending into a field. He provided an additional statement about three months after the accident, indicating that the aeroplane was travelling ‘at least 200kt, it could have been 230kt’, just before the left wing failure. The pilot held an airline transport pilot certificate with an aeroplane multi-engine land rating, plus a commercial pilot certificate with aeroplane single-engine land and lighter-than-air balloon ratings. He also held a flight instructor certificate for aeroplane single- and multi-engine land, plus type ratings for the Airbus A320, Jetstream BA-3100, Embraer EMB-120, and Saab SF-340. He also had a repairman experimental aircraft builder certificate for the accident aeroplane as well as for the DR-107 experimental amateur-built aeroplane. According to FAA airworthiness records as well as publicly available information, the aeroplane was a two-seat, original design, canard-style aeroplane manufactured by the pilot. It was powered by a modified GE-T58-8B turbine engine, which was originally designed for a military helicopter. The aeroplane received a special airworthiness certificate on 30 June 2014. Earlier in the year, the accident pilot described the design, manufacture and operation of the accident aeroplane in a narrated webinar entitled So, You Want to Build a Jet?, which was hosted by the Experimental Aircraft Association.
“A cockpit video showed the left winglet moving forward and aft about four inches” 46 | FLYER | September 2020
During the webinar, the pilot reported that the accident aeroplane had a Vne (never exceed airspeed) of 250kt indicated airspeed (KIAS), or 310kt true airspeed, and stated, “Have I been past that (airspeed)? Yeah, it was exciting, and I won’t tell you how far I went past it.” He explained that the aeroplane was ‘airframe limited’ because the jet engine could propel the wings faster to loads that they could not tolerate. He also reported that the aeroplane’s first flight was in 2017, although the aeroplane had received its FAA special airworthiness certificate in June 2014. Examination of portions from the internal left wing structure was performed by the NTSB Materials Laboratory in Washington, DC. This examination showed that the upper wing surfaces and the upper spar cap sections had areas that were consistent with a resin-starved or dry laminate. These areas were also consistent with an adhesive disbond between the respective faying surfaces. This adhesive disbond was consistent with a lack of impregnation and interaction of the resin into and with the fibreglass fabric, resulting in a lack of strong adhesion between the wing skin and the spar cap. These issues were consistent with a fabrication problem during manufacturing of the layup rather than wear over time or an environmental degradation failure. Additional information: The first witness reported that about two months after the accident aeroplane’s first flight in 2017, a flutter event occurred with its left wing. The witness stated that he saw the flutter event on a video that the accident pilot had shown him. The video camera appeared to be mounted on the left wing, and the video of the flutter event showed the left winglet moving forward and aft, in a back and forth motion, about four inches and about one revolution per second. The witness
Mark Mitchell
While we all applaud a light touch to the regs that govern the way we go about our flying, sometimes that isn’t enough to protect us from ourselves. Steve Ayres takes a look…
