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
4 August 2020
Many 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?’
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.
“A cockpit video showed the left winglet moving forward and aft about four inches”
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. 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 thought that the airspeed during the flutter event was 232 KIAS. He reported that he was unaware of any structural repairs or modifications to the aircraft after that flutter event.
The Jodel D117A was being operated on a Permit to Fly and had no modifications adapting it for the disability of the pilot, a left forearm amputee. When flying the aircraft, the pilot used his right hand to control the throttle. To operate the ailerons and elevator, a rose jointed adapter which was secured to the prosthesis on his left arm, was attached by an interference fit to the control column. All other controls were conventional.
“As the pilot flared, the prosthetic adapter became disconnected from the stick”
The pilot was flying circuits with a wind slightly from the left and steady at 10kt. On the fourth circuit, the pilot established the aircraft on the final approach and trimmed for 50 KIAS.
At about five feet above the ground, while the pilot was flaring the aircraft, the prosthetic adapter became disconnected from the control column.
The aircraft reverted to its trimmed shallow nose-down attitude and subsequently struck the ground. The landing gear dug into the ground and folded back under the wings, and the nose of the aircraft pitched down further, damaging the lower engine cowl and the propeller, and shock-loading the engine. The pilot was uninjured and, after making the aircraft safe, exited without difficulty using the left cockpit door.
The pilot was a doctor with extensive experience in the management and prosthetic rehabilitation of people with acquired and congenital limb loss. He had held a flying licence for almost nine years and had flown the Jodel for almost five, of which he had flown more than two years and more than 230 hours using the prosthetic adapter.
The reissue of the LAPL medical certificate required the pilot to undergo a medical examination, and a medical flight test (MFT). The medical examination, conducted by an Aeromedical Examiner (AME), focused on the medical aspects of the amputation, and included an assessment of the prosthesis and its fitting to the limb.
The MFT was carried out by a chief flying instructor (CFI) and included discussions about the possibility of disconnection of the adapter and actions to mitigate the consequence of any such occurrence.
Typically, this would involve taking hold of the control column with the right hand to enable the pilot to retain control of the aircraft, while he reattached the adapter before resuming normal control. During the MFT the pilot demonstrated this and the CFI noted the prosthetic adapter was ‘solid, well made with no play’. Subsequently, the pilot practised regaining control while flying following a disconnection of the adapter from the prosthetic on a regular basis.
Conclusion: The aircraft landed heavily when the prosthetic adapter detached from the control column late in the approach and the pilot was unable to regain control before touchdown. The pilot met the requirements for medical fitness to fly, but there was no engineering rating by a suitably qualified individual of the interface between the prosthesis and the aircraft controls.
The lack of a secondary device securing the prosthetic adapter to the control column meant its security was solely reliant upon the interference fit.
The CAA is taking action to ensure there is proper engineering oversight under similar circumstances.
When hearing about some accidents it is difficult not to think that, at best, it was a bit of Murphy’s Law – ‘anything that can go wrong will go wrong’ – and at worst, ‘an accident waiting to happen’. And this despite all those involved with aviation working tirelessly to ensure that inspection regimes, design authorities and legislation operate to give us the freedoms we as aviators crave while keeping us safe.
Regrettably, as individuals we don’t always play the most constructive role and no amount of legislation, rules and oversight would be enough. True, when things go wrong they can do so without warning – and quickly. But not always. Often there is a bit of a heads-up, a certain ‘je ne sais quoi’, which gets our antennae quivering and has us delving under the bonnet or at least muttering questions behind a raised hand to a trusted colleague. And yet things still fall through the cracks.
In the case of the Jet Eze, the pilot openly admitted to exceeding Vne and experiencing flutter. Something that would set alarm bells ringing with most of us and leave us questioning the cause and the potential damage, all the while thankful that we had survived the flight. Despite the pilot holding numerous flying and engineering qualifications it was not enough to keep him safe.
And even when we get things mostly right, as did the Jodel pilot in producing a cleverly designed prosthetic adapter, no one spotted the weak link in the chain.
Even though he was able to demonstrate inflight that he could relocate a disconnected adapter, to be able to do so at a critical phase of flight was always going to be problematic. In this instance, new CAA legislation should prevent a repeat accident by requiring some proper engineering oversight.
While in the UK we might not always appreciate that level of regulation and bemoan how sometimes it stifles experimentation and innovation in aviation, it does protect us from some of our greatest excesses and for the vast majority, at least, keep us safe.
However, it will never pick up everything, and if something unusual happens or we find ourselves operating on the edges of what might be deemed ‘normal practice’, it might be worth taking a step back, reflecting a while and seeking a second opinion. Which, of course, we will do, listen to and take action.
