Someone's Been Looking Out for Me...
Accident investigation; why did the winglet fail?
By Tim Sullivan, firstname.lastname@example.org
June 13, 2009. Placerville, California. Aircraft: Long-EZ. Registration: N7999H. Injuries: 1 Uninjured. The pilot reported that he applied light pressure to both the left and right brakes following an uneventful landing. The left brake and rudder were inoperative, and the airplane began to veer to the right. Unable to apply brakes or left rudder, the airplane exited the runway and impacted an unoccupied passenger van which resulted in structural damage to the right wing, and fuselage, with substantial damage to the front of the van. Examination of the brake system by an FAA inspector revealed that the probable cause(s) of this accident was the pilot’s inability to maintain directional control during the landing roll due to a jammed brake/rudder cable. But why?
It’s taken 16 months to finally write this report about my plane’s demise on June 13, 2009. I waited due to a few reasons including the finalizing of reports to the FAA, National Transportation Safety Board, and insurance company, as well as getting the plane back into the air, but mostly to determine the cause which led to the events that follow.
On June 13, I was at the Golden West Regional Fly-In at Marysville, California. It was a normal, hot day at the event. When I was done with my volunteer work, I walked out to my plane which was parked facing outward along the closed runway. I did my normal walk-around. Things looked fine except my right rudder had been pushed out and stuck in that position. This happens on my plane when a gust of wind comes by, and it’s not an issue. There was no wind that day, so the locks weren’t in place. I popped the rudder back into place and completed my walk-around, all normal and ready for flight.
I climbed in my Long-EZ (one of many designs by the legendary Burt Rutan) and waited for my turn to taxi out to the active runway. Cleared for takeoff, I rolled out and rotated. At rotation I noticed (for a split second) a slight yaw to the right, but I figured it was the result of a hot day in the valley and a small thermal off the runway. I switched over to flight following and proceeded on a 120-knot (indicated) climb to 7,500 feet where I trimmed for cruise. The trip from Marysville to my home airport, Placerville, is 20 to 25 minutes. As my airspeed came up to cruise (170 knots true), I had a flashback of an uncoordinated turn from my taildragger days. I looked down at my Dynon D180 and saw the ball was toward the left and completely outside the center bars. “Yikes, that’s a lot of yaw,” I said. My left butt cheek confirmed the yaw as well.
Figuring It Out
At this point I was a little more than halfway home and started to diagnose the anomaly. The most likely source of such a yaw was the right wing. The rudder was neutral. The aileron was neutral with no indications of having a hinge problem. The seal tape was flat and not cupping along the leading edge. The vortilons were all on and appeared straight. Nothing I could see from the cockpit was indicating the cause of the yaw; of course I could only see a portion of the wing.
As I approach the airport vicinity, I overtook a friend who was headed back to Placerville in his RV-9A. I asked him to come up alongside as I took a slow left turn so he could look under the right wing. Maybe the wheel pant had an issue or the speed tape was coming loose. “Nothing,” he reported. At the time, the IAS was down to about 90 knots and we were circling over the airport at 5,000 feet. I noticed the yaw was nearly gone, so I figured this was an induced yaw and told him I would increase to 130 knots indicated airspeed. As we approached 130, he radioed, “Get that *&%#$%^ plane on the ground – the right winglet is coming off!”
The following events were fairly intuitive, and contrary to what I’ve heard time and again from others about moments of high stress, time didn’t slow down for me.
I immediately cut the power to idle, radioed an emergency on the local frequency, turned left (we were about midfield still at 5,000 feet – about 2,500 above ground level), and entered a high downwind left pattern for runway two-three. The RV-9A bolted for the runway, landed in front of me, and pulled off at the high-speed turnoff. I slowed the plane down as much as I could while losing about 2,000 feet of altitude. As I turned base to final, I was flying so slow that I applied a little left rudder. It wouldn’t move at all. I radioed to the RV-9A that I may have a secondary problem with the left rudder, and since applying full rudder engages the brake, I possibly had a brake issue, too. But I was committed; I wasn’t going to attempt a go-around with a right winglet coming off. At this time, however, from my vantage point, I still couldn’t see any visible signs that the right winglet had a problem.
On final the speed was really slow, basically just about full aft stick, using the throttle to modulate the descent. With the plan over the numbers, I chopped the power and held it off the runway as long as I could, which wasn’t long considering my slow final speed.
Touching down the mains, I held the nose gear up as long as possible. When the nose gear finally touched down, I “tapped” the rudder pedals. No response from the left, but the right worked; I was now on a very slight angle to the right and going off the runway.
Before we go on, here’s a little description of how the rudders work on the EZs. Each winglet acts as a vertical stabilizer with a rudder. The rudder, however, only deflects in one direction, that being away from the aircraft's centerline. The left rudder pedal is connected by a single cable to the left rudder, same with the right. Each side is 100 percent independent of the other. Pushing the left rudder pedal deflects it to the left. Releasing it allows the rudder to return to neutral via either air pressure or a small spring. Pushing the left rudder pedal all the way to what would normally be a stop engages the braking system via a traditional hydraulic master cylinder. Same for the right – again completely independent. Pressing them both at the same time causes the rudder system to act more like spoilers – all drag with no yaw.
Once on the ground, the routine is to push both rudder pedals to the limit, deploying each rudder/spoiler, creating aerodynamic drag while engaging the differential wheel brake system. So, long story short, it’s impossible to apply either brake cylinder without deploying rudder, and if the rudder is jammed for whatever reason, the brake (on that side) is inoperable, too. ~Pat
As the perpetrator of the ensuing ugliness, I started to shut down electrical systems except the radios. Next was the fuel valve, and then I went for the nose gear ratchet; retracting the nose gear is an effective braking system. In hindsight I should have cut the engine, but I had it in my mind the fuel valve was more important and that it would do the same job…eventually. Just as I was about to flip the tiny little ratchet switch on the gear retract, the panel became a blur. I was off the runway with no chance of getting the switch over.
The Right Turn
I crossed the 50-foot-wide dirt area, again at a very slight angle until I wound up on the parallel taxiway where I would try again to dump the gear. Oh *&^%! The RV-9A is on the taxiway right in front of me with the prop stopped! I radioed to tell the aircraft to get out of the way. The next moment was a split decision. I had one right brake working, and now no matter how hard I tried, the left was jammed. The made the decision to use the brake to “aim” for one of three fates: 1) a very steep drop off the side of the airport (the Placerville airport is built on a hill top that was shaved off) which meant a hard and early braking and likely serious injury; 2) colliding with an old beat-up Dodge Caravan that had been parked and left there, I believe, by Lindbergh; and 3) take out a row of planes. I decided the van was toast. I hit the brake hard at just the right time to smack into the front of the van.
up and over the hood with the fuselage and over the roof with the right wing.
With unbelievable luck, which is why I titled this article “Someone’s Been Looking Out for Me…,” the nose hit mid-grill of the van, and as I was making that hard right turn, the right wheel was off the ground as the plane tipped to the left. That was another bit of luck because that brought the wing up high enough to allow only the outboard portion of the wing to strike the top of the van’s windshield/roof line and completely avoid hitting the right strake/fuel tank. Whew!
The plane bounced off the van and skidded about eight feet to the left. By this time the nose gear was collapsed from the impact. The plane came to a rest, and I popped the canopy, shut everything else off, got out, and sat on the ground in disbelief of what I just went through. My friend, the RV-9A pilot, ran up to see if I was hurt. Not a scratch. Thanks, Burt.
The plane came to rest on the other side of the van. From this camera angle, imagine a straight line from the van to this point. That was the direction of travel.
The insurance declared the plane totaled. The damage report is as follows:
- right wing – buckled, basically destroyed
- right winglet – total structural failure. You could wiggle it with two fingers.
- main gear – completely broken off all the extrusions while still in the hell hole
- main gear – cracked at midpoint. The gear took almost all the energy of the impact with the van. It caved in the whole front end (of the van) as it flexed at an estimated 45 degrees inward.
- wheel pants – toast
- one inch of the prop tips – gone. We performed the required accessory gear check; it was fine, so the prop strike was benign.
- left lower winglet – toast as the plane impacted and slid to the left
- left winglet – cracked at the base and could wiggle with some effort
- nose gear assembly – toast. The nose had a slight breakage on the right as it impacted, then went up and over the van.
- right canard tip – cosmetic damage.
I collected the check from the insurance company for the full hull value and bought back the carcass. I knew the panel and engine were worth way more than what I paid to buy the plane back. I started a search for another plane with the help of my friend David Orr. With every plane I looked at, I could see a lot of work to get it up to the same standard that I had with my plane. After four months, I gave up and decided to have the plane rebuilt. The plane went down to the Los Angeles area for the rebuild and hopefully will be back by the end of October 2010.
So what caused this one-two punch of failures? First, if you’ve read the report from Marc Zeitlin (Marc was featured in last month’s Experimenter) late last year, you’d know the winglet was cut off and examined at Scaled Composites, where Marc works. The basic finding was that the winglet was filled with microballoons (aka "micro" a nonstructural filler) rather than flox (a filler considered to be structural) at the inner root of the winglet. The best we can speculate is that the rudder was pushed out at the Marysville airport by a very large dust devil (witnessed by many) as it passed over my plane and the Stearmans on both sides of my plane. The dust devil was large enough to spin the Stearmans around, but neither made contact with my plane. The direction was such (as reported by witnesses) that it hit from the rear of my plane while passing over and to the right, thus whacking the right rudder/winglet. This must have been just enough force to snap the micro deep inside the inner winglet joint but not crack the outside paint along the same area.
The culprit: a tiny copper ferrule
So why the problem with the left rudder pedal, you may ask? When I was in cruise and noticed the yaw, I pressed on the left rudder to see how much force it took to straighten out the plane, which turned out to be a lot. After the plane was back in the hangar and many hours of going over the controls with the insurance company and the National Transportation Safety Board, the most probable cause was that the plane had retractable rudder pedals for the rear passenger, and the copper swage that made up the cable attachment caught on one of the mounting holes in the slide track. What caused the cable to continually press against the slide track is anyone’s guess. Nevertheless the rear rudder pedals are now gone.
Besides having all the repairs and replacements done, I had the left winglet removed and checked for the same micro in the inner joint. Yep, it was there. The winglet was reattached correctly. I also had the plane rewired with a new panel. Chris Randall did this work expertly. The Dynon D180 panel was replaced with a 10-inch Dynon SkyView. The old radios were replaced with a Garmin SL30 and a GTX 327 transponder, and GPSMap 496 was panel mounted with the gizmo. They all talk to each other. There are no steam gauges left. A backup digital altimeter and airspeed indicator was installed. Also a secondary bus was wired into the electrical system. An electric nose gear lift was installed with auto extension and backup battery, and many more improvements were made as well. I used up the insurance money and then some to have all this done.
It’s been 16 months since the plane has flown. It will be done just in time for the bad weather winter season. I can tell the plane is almost done by looking out the window at the rain and clouds here in Placerville. As some of you may know, my call sign is “Wizard.” But my nickname is “Black Cloud,” given to me by the canard group in Arlington, Washington; every time I call for a PIREP to the annual Arlington Fly-In, they say “severe clear,” but as I approach, the weather goes down the tubes. So the plane must be about done.
I hope to fly soon and see you all out there next flying season. Look for the yellow and white EZ. I hope this account can impart some helpful information to the canardians – if nothing else, it was nice to get all that off my chest.
See ya all!