Experimental Jet Crashes in Mojave

8 Sep 17 7 Comments

On the 13th of May in 2016, a Seguin Quickie, registration N68TQ, crashed in Mojave, CA. If you don’t recognise the aircraft type, that’s because there’s only one in existence. Or was.

The Seguin Quickie was an experimental amateur-built kit plane: a single-seater composite aircraft. It was designed and constructed for air racing by commercial pilot Elliot Seguin, who worked as a professional test pilot for a general aviation aircraft manufacturer, and his colleague Justin Gillen.

This crash is incredibly well documented because, in addition to the NTSB report, there is also the Twerp Report which has been made available by Elliot Seguin. Smithsonian’s Air & Space magazine published a feature in June called Elliot and Justin’s DIY Jet full of details and with in-depth interviews of the men. Finally, the test flight was being filmed for Red Bull TV and the footage of the crash has been published online. The video, newly released, is what drew my attention to this accident.

Last Moments of the Seguin Quickie affectionately known as Twerp
Last Moments of the Seguin Quickie affectionately known as Twerp

From Air&Space’s Elliot and Justin’s DIY Jet:

One day [Seguin and Gillen] spotted an opportunity in the hangar right next door: Hanging like a museum display was a Rutan Quickie Q1 homebuilt—a featherweight taildragger designed by Scaled Composites founder Burt Rutan—that had been abandoned by its original owner before it ever flew. Seguin and Gillen’s neighbor had rescued it from the airport dumpster, then held onto it for a decade, always intending to do something with it.

Of the many oddball Rutan designs, the Quickie is one of the oddest. It has tandem wings, with the main gear located at the tips of the main wing. It has the profile of a wasp and the aura of a spaceship.

The two men got permission to ‘do something cool’ with the abandoned aircraft which had never been finished. They modified the kit plane into their own design: the Seguin Quickie. The major modification was to ditch the single piston engine and propeller in favour of two TJ40-G1 turbojet engines.

These engines are not actually designed for aircraft use, or at least not any aircraft with a seat in it.

From the Operation and Maintentance Manual for the engines:

“The TJ40-G1 turbojet engine is designed exclusively for model aircraft and is not suitable for any other purpose. Never use it for people, objects or vehicle; it can only be used for properly designed model aircraft. Any other use can result in injury or death.”

The two engines weighed 8 pounds each, quite a departure from the 80-pound Quickie engine. They were mounted one per side on the lower fuselage, just aft of the cockpit. The nose of the aircraft was extended three feet to stabilise the weight and balance of the aircraft.

From Air&Space’s Elliot and Justin’s DIY Jet:

“The obvious solution is to put the new engines where the old one was,” says Seguin. But then the hot exhaust, traveling the whole length of the airplane, would bake the fuselage.

Instead, they moved the engines to the back and added two additional fuel tanks—one in the new nose and one under the rear wing spar—and let gas flow between them. Then they built a new nose using a mold they had created from 50 pounds of foam purchased at a hardware store, and filled it with ballast to re-balance their airplane.

Neither Seguin nor Gillen had ever flown a Quickie before and were unable to find one for transition training. The initial flight tests focused on basic handling and landing procedures. Not surprisingly, they were worried about the engine performance, although perhaps not as worried as they should have been.

From the Twerp Report:

The biggest risk to the program was engine reliability (experimental engine). Engine reliability is the highest risk of the program because the engines are new and have not yet flown. The Quickie airframe was chosen because its low drag meant that in a single engine situation it could climb on one engine, and if both engines were lost the glide ratio would also be favorable. From a procedural standpoint the decision was made to minimize power changes near the ground and in the event of an engine failure the second engine would be shut down and the airplane landed without power, likely straight ahead.

The engines proved even more problematic than they expected. The Twerp Report refers to several uncommanded shut downs of the engine while idling on the ground, which was put down to the engine’s built in starter generator being unable to generate enough electricity to support the engine at low power settings. Having found that running the engines at or above 20% power greatly increased the reliability of the engines, Seguin and Gillen decided that it was reasonable to continue with the flight test after a series of low- and high-speed taxi testing across two days.

From Air&Space’s Elliot and Justin’s DIY Jet:

“I think we both knew that we hadn’t licked the engine failure problem all the way,” says Gillen, “but we had rationalized it by saying that the worst place for the engine to fail is on the takeoff run.” In that scenario, Mojave’s 12,000-foot runway gave them plenty of room to land safely after liftoff.

The initial test flights that morning were successful but showed that the aircraft had significant problems landing as a result of the poor ground handling characteristics.

The first landing at 70 MIAS (miles per hour indicated airspeed) with a tail-wheel first touchdown at 62 MIAS, culminating in a smooth landing.

Seguin took the plane up again. This time for the second approach, he maintained 85 MIAS in order to keep the power up in case of engine failure. The goal was to minimise the time spent below VMCA: the minimum speed in the air where directional control could be maintained with one engine inoperative, with a maximum of 5° bank towards the good engine.

However, the landing went badly. The main gear touched down first and the aircraft swerved dramatically on the runway. Seguin and Gillen agreed that a 70 MIAS approach should be used, even though that extended the time spent below VMCA.

There’s no published crosswind limit for the Quickie and the two had agreed to a maximum crosswind of 5 knots for the initial test flight. After the second flight, the experimental jet had a total of 0.8 hours of flight time.

Now they were disappointed: desert winds increased and it looked as if testing was finished for the day. The crew and the Red Bull team took a break for lunch. As they did, the weather appeared to calm. The winds dropped and they found that the crosswind component was 7 knots, only slightly above their agreed maximum of 5 knots.

From Air&Space’s Elliot and Justin’s DIY Jet:

“Man, it would be great to get one more flight off,” Seguin said. In his memory, the team agreed it was a good idea. Or maybe he means that no one actively objected; Gillen remembers it differently. “I long ago decided that Elliot makes his own decisions on go or no-go, and I would do the same for myself,” he says. “I thought, ‘Well, I wouldn’t do that, but it’s not me.’ ”

Also, both men wanted to know more about the crosswind handling of the aircraft and this must have seemed like a good opportunity. Later, they also said that perhaps they were suffering from ‘Kodak courage’ with the Red Bull team filming their every move.

Whatever the justification, it was agreed that Seguin would fly a few circuits in the pattern, with a low approach before going around, to explore the crosswind handling capabilities before landing for the final time that day.

They towed the aircraft back to the runway and ran it at 20% power for three minutes to recharge the batteries. Then Seguin applied full power for his take-off roll down the long runway.

The wind shifted and began to gust again just after the aircraft lifted off. Conditions weren’t good. Seguin pulled back on the power to descend, cutting off the test flight to land.

At just 200 feet above the runway, the wind gusted, rolling the aircraft to the right.

From the Twerp Report:

On short final to 12 I applied full crosswind controls and found they weren’t enough to parallel the runway. I continued the descent, approaching at 70 MIAS, and setting up to land with a slight cross track diagonally across the runway. With five feet to go, there was a large gust from the right that rolled the airplane left more than 45°. I decided to go around and selected full power.

Applying full power I heard the engines spool up, I felt the thrust push me back in my seat, and I pulled the nose up to climb attitude.

The left engine failed.

The aircraft rolled towards the dead engine. Seguin attempted to recover but now the nose was pointing straight towards the ‘boneyard’, a storage area for aircraft retired from service.

From the Twerp Report:

We had briefed that in the event of an engine failure the second engine would be shut off and the airplane landed straight ahead. Without a suitable landing spot in sight I kept the right engine powered up and attempted to climb. I reduced the right engine to less than forty percent (predicted PFLF) and then added and removed power working on the Lat/Dir problem that was pushing me into a downwind turn and the boneyard/747s. The airplane clearly needed more speed to become controllable but I couldn’t climb high enough to lower the nose and accelerate.

Seguin was heading straight for one of the Boeing 747s of the boneyard. He maintained 30-40% thrust on the right engine to try to clear it but couldn’t regain directional control: the aircraft kept slewing left. He only just cleared the B-747, just to find two more 747s and a trailer on the other side. He wasn’t going to make it.

From Air&Space’s Elliot and Justin’s DIY Jet:

Increasing the power and pulling away, he soon found two more 747s in his view. He couldn’t go over; he couldn’t go between. It was game over.

And then he saw the trailer.

He didn’t know what was inside, but he figured—perhaps foolishly—it had to be softer than an airliner.

He pushed the nose down, pulled the throttle to idle, and closed his eyes.

An only slightly less dramatic description is in the Twerp Report:

I could not raise the left wing and the airplane was consistently in a hard slip to the left with the nose slicing left. Once it became clear I wasn’t going to get above the tails of the 747s I reduced power to get lat/dir control and between the tails. As I got through the tails and looked deeper into the boneyard, I was below everything in front of me (specifically a silver convair 880) and there was no open ground to land. I decided climbing was the only way I would survive. I added power; the slip got worse; the airplane stalled and rolled left. An abandoned mobile home sat in foreground in front of the broadside of two 747s that were much taller than I could climb. I accepted the mobile home as a better accident site than the landing gear of an airliner and pulled the right engine back to idle. At this moment I remember feeling exhausted that the fight was over and relieved that the puzzle had been solved, no matter how bad the result.

The Trailer and Wreckage

The Seguin Quickie struck the south side of the office trailer with enough momentum to crash straight through it. The canards, wings, vertical stablizer and one engine were ripped off of the fuselage, which ruptured just behind the cockpit. Amazingly, the cockpit remained relatively intact and the fuel cell was almost intact.

From the Twerp Report:

I closed my eyes before impact. When I opened my eyes I was on the ground in the boneyard, canopy and visor were gone and the sudden change in sunlight was a surprise. I visually inspected the limbs that I could see. Then I moved my neck and back and felt nothing strange. I picked up my arms and visually inspected for blood. Then did the same for my legs. Finally I unlatched the seatbelt and stood up. Shortly after stepping out of the wreck Justin Gillen and the crew came around the corner in the chase truck. Airport security showed up roughly 5 minutes later. The ambulance arrived after that, and then the fire department which drove from Cal City.

Here’s a clip from the Red Bull filming of the flight.

Gillen was frantic to get to Seguin, shouting into the radio. “Tower, I need to get to the boneyard right now!” That’s when Seguin stood up so that Gillen could see that he was still alive.

The final bit of luck was that there was no fire. Still, it’s hard to imagine how Seguin survived.

What had gone wrong? Unfortunately, there wasn’t enough left of the aircraft to be sure.

From the NTSB investigation:

There was insufficient evidence to determine the reason(s) for the loss of engine power, and none of the three most likely causes (fuel flow interruption, air flow interruption, or flameout due to rapid and large throttle input) could be definitively ruled out.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
A loss of engine power for reasons that could not be determined based on the available information.

Collected Wreckage

At the heart of it is the question of an unstable and unpredictable aircraft and a test pilot who was, perhaps, a little too invested in making sure that it could fly. According to Air and Space magazine, he’s still hoping to construct a lighweight racing machine by attaching the model aircraft jet turbines to a small aircraft, maybe a Cessna.

If you are interested in learning more, I highly recommend the Air & Space magazine article which I have quoted above (I wish I could write like that!): Elliot and Justin’s DIY Jet.

You might also enjoy the 45-minute video by Red Bull TV. It’s available online as Season 1 Episode 1 of their Breaking the Day series: Mojave Test Pilot.

Category: Accident Reports,

7 Comments

  • Considering the level of experience these guys (professional test pilots !) have, their naivety when it comes to building AND continuing to test-fly an obviously unstable and unreliable aircraft, put together from the remains of another unfinished project and powered by patently unsuitable – and unreliable – engines beggars belief.
    “A fine mess…”
    Fortunately, like the antics of Laurel and Hardy, it did have a happy ending.

  • What incredibly brave chaps! This is the true spirit of what amateur aviation is about (although these guys were pros I note but their airframe and engines -WOW!) using model aircraft engines – very WOW) I used to test to RTCA-DO160 and the provisions of that standard all came back. Interesting that the engine’s generator would generate 200 watts above 20% engine power however on idle would generate less. DO-160 checks for such things. Given the experimental nature of the endeavour I am surprised that a flight recorder, monitoring such things as rpm/battery volts was not installed. A must I would have thought. But REALLY WELL DONE TO THE GUYS AND THEIR PIONEERING SPIRIT.

  • John’s comment put this effort in another light.
    I am not so sure that I can agree with him, though.
    I admit that I have done things in my flying career that, looking back, I was lucky that the CAA, RLD, Luftfahrtbundesamt, FAA, IAA or whatever – never mind the accident investigation board – never heard about. In other words: I got away with it.
    And I retired with about 22.000 hours in my logbooks, accident-free.
    Yes, modifying a not quite finished project, fitting different engines, not deemed suitable for manned aircraft, and test-flying it can be attributed to a “pioneering spirit”.
    But as professionals, I reckon that they also should have been able to research and consult computer programs to check the validity of what they were trying to find out by trial and error.
    The error, not having been eliminated beforehand, only by the grace of our Maker did not cause loss of lives.
    So: brave? Yes. Pioneering? A cautious “yes” too, but in the balance, what these guys did most certainly had elements that I do not hesitate to call “foolish”.
    But I must admit that I am glad to hear that they got away with it.
    Because in my younger years, I too was foolish on a few occasions.

    • I agree with you Rudy, a pioneering spirit is good, but these guys went beyond that. It sounds like they had a firm crosswind limit they decided to avoid because of their personal investment in the project, and they made individual decisions of whether or not to fly – procedures and planning are there on purpose to keep personal feelings from affecting safety!
      I have read of other aircraft flying with model aircraft jet engines, but they have been done carefully and worked up over time – the haste to fly no matter what and without addressing known problems is what caused this accident. These guys knew better and should have acted better – if I was a potential employer of theirs, this accident would make me think twice about hiring them.

  • Rudy: Computer simulations are more difficult than you seem to think, especially for individuals who probably don’t have the funding level of a major aerospace firm. Even for the aerospace firms, those simulations are difficult and expensive, and so are the wind-tunnel experiments that back them up.

    This report makes it clear that an experienced and daring professional test pilot was experimenting on his own with a fairly far-fetched handbuilt aircraft. His skills and experience, plus a goodly dose of luck, did get him through without major injuries. But given the description of what he was trying… well, it’s probably just as well for all concerned that the plane got totaled. ;-)

  • Plenty of other experimental homebuilt aircraft have flown with engines not rated for manned flight. So I wouldn’t do a knee jerk reaction against the concept. It’s a homebuilt; you can make your own choices in design & development. But if one wants to argue that they should have done more engine testing and investigation first, sure! Sounds like the Quickie doesn’t have a lot of control authority; it never needed as much in its original form as a single engine.
    So much for having a big airport with a long runway, if one ends up pointed towards huge obstacles….

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