Trailering Tail-First Problem

[jiott]

Just a heads up about a serious problem I had when trailering my SS7 tail-first.

Due to an emergency landing at a rural airport, I borrowed a trailer to get my Kitfox back home, about a 130 mile trip. The trailer was built for a Kitfox and worked very well; it was a tail-first design. I immobilized the rudder so it wouldn't flap in the breeze, and tied the control stick fully forward to immobilize the elevator also. I drove the 130 miles home at about 50-55 mph because I could see in my rearview mirror that the wind was pushing very hard on the elevator. Got it home and everything seemed fine. After flying for 25 hours I was doing a casual inspection and noticed the rear elevator control pushrod had quite a wow in it. I took it out and inspected it and found a pronounced wow but no kinks or cracks, so I straightened it and reinstalled it and everything is fine now.

The cause of the wow was obviously the trailering. The elevator was in a down (nose-down) position, so the wind force from highway speed caused a compression (buckling) load on the pushrod. It was a strong enough force to permanently bend that pushrod, which really surprised me. I can't imagine the damage that would have been done if I had traveled at 65-70 mph. My takeaway from this is to never trailer tail-first without immobilizing the elevator by some means that doesn't put a compressive load on the control pushrod. Probably many of you already know this, but FYI.

[ken nougaret]

I trailer tail first for every outing. Only 5 miles and 50 mph. But I put the elevator slightly up till it touches the leading edges of the flaperons. I put some thick clear tape where the contact is made. So far, so good. But thanks for the heads up.

[Benbell4140]

I’m not exactly sure when the change was made but I’m pretty sure the newer kits have more bellcranks in the elevator control system than the older 5’s and possibly early 7’s. Also the older models had an aluminum push pull rather that than the newer 4130 chromoly push pull rods. Still a good idea to keep an eye on things regardless of the system. Again, I’m not sure which models have the newer revision.


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[Kitfox Pilot]

Thanks for the heads up Jim. Just wondering what caused the emergency landing?

[avidflyer]

I have several sets of gust locks. 1 x 4 boards with foam rubber on them. Bolts hold the ends together. Have two for the elevator and one for the rudder. Wouldn't trailer a plane without them. Even conduit with foam pipe insulation would work, and tightly tie the ends together to keep things from flopping around. I've sold two different elevators from Avid Flyers to people who didn't think they needed gust locks. If it's broke when you get to where you were going, that's bad enough, but if it breaks in flight, it will really ruin your day. JImChuk

[4Hummer]

I use lots of "Gust Locks" when I trailer




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[avidflyer]

Yes, gust locks are a must. One other thing I would suggest is to support the back end of the plane on something besides the tailwheel. With the wings folded, that is a lot of weight on the tail wheel and tail spring. Here is what I did before hauling this Kitfox 4 1500 miles from Texas to Mn. The trailer was set up for my Avid Flyer, so I had to take off the tailwheel to make things work, but this should give you the idea of what I'm saying. JImChuk

[jiott]

Thanks for the heads up Jim. Just wondering what caused the emergency landing?

Harlan, its a long story, but here it is:
An engine out event I had due to a water pump drive gear failure on 4/9/2021 at 952 TTSN hours.

On April 9, 2021 I was flying low (about 400') in my Kitfox SS7 over the Deschutes River, OR in the bottom of the deep canyon, heading for Bull Run, a backcountry dirt airstrip about 5 miles ahead of me. All instruments were showing normal readings and the engine was running smooth. Suddenly without any warning the engine stopped instantly without any clank or unusual noises. With nowhere to land except the river or rocks and brush on the narrow shoreline I pitched to a 65 mph best glide speed and tried a restart; it started right up and seemed to run fine. I climbed out of the canyon and made a normal landing at a small rural airport (Wasco State) about 15 miles away. However, during this 15 mile flight, the CHT's started to climb into the red, reaching about 320 F and leveling off there. The oil pressure and temp remained entirely normal thru the whole flight until I shut off the engine. When I got out of the plane oil was dripping out of the bottom of the cowling, but no coolant had leaked out and the coolant system was full with no steam coming past the pressure cap. Oil of course was way down and didn't show on the dipstick, but there must have still been enough to maintain oil pressure and temp. With the oily mess I couldn't spot any cause, like broken hose or loose clamps or fittings. So I arranged to trailer it home to evaluate it.


After cleaning up the oil that had sprayed all around in the engine compartment I was able to see a hole punched thru the bottom of the ignition housing near the water pump weep hole. A gear tooth was partly sticking out of that new hole that had been punched. It was right below where the water pump drive gear is located. It is in a chamber that has engine oil to lube the drive gear, so of course oil started dribbling out of this small hole. Apparently it was a slow enough leak that it gave me time to fly about 15 miles to Wasco airport and still maintain oil pressure and normal oil temperature. However, the water pump must have quit operating because of the broken drive gear so no water was circulating even though the coolant system remained full, causing my overheated cylinder heads. The moment the water pump drive gear broke must have mechanically jammed the engine, causing it to suddenly stop. When I activated the starter about 10 seconds later it must have pushed the broken piece thru the housing and cleared the jam, allowing the engine to restart and continue running, even though oil was running out the hole. The ignition housing and water pump drive needed to be replaced, possibly the overheated cylinder heads, and inspected for other damage.


This was a very unusual occurrence, but was related to some work I had done a year ago (4/29/2020 at 850 hours) by Aircore Aviation (Jim Scott, A&P/IA), in Arlington, WA, an authorized Rotax Repair Center. He replaced the ignition housing the first time due to a crack in the top of the original housing. The replacement housing was remanufactured unit purchased from South Mississippi Light Aircraft which already had a water pump and drive assembly installed by SMLA. Aircore Aviation is no longer in business and the owner has retired. So I shipped the engine to SMLA to evaluate damage and repair. Findings were: the Arlington shop mechanic had carelessly let a starter idler gear thrust washer slip out of position when installing the new ignition housing/starter assembly and it dropped down into the bottom of the case unknown to anyone; after I flew it for about 50 hours the washer finally worked its way into the water pump drive gear assembly and caused the sudden engine stoppage in the canyon; broken gear teeth and other pieces then ruined the camshaft drive gear and bearings, scarred up bearing journals in the crankcase, and damaged some pistons and bores. The engine was trash; would have cost more to repair than it was worth as a half TBO (952 hrs) engine.

The good news is that Jim Scott, the retired mechanic, stood behind his mistake when I contacted him and sent me $8000 as an insurance payment, and I got $2000 from SMLA for core value for my trashed engine. That gave me $10,000, half the cost of a new engine, so I purchased a brand new 912uls and installed it. I have been flying it now for 30 hours and everything is working fine. My 8 year old, 1000 hr, Kitfox SS7 is like brand new, and I didn't crash or get a scratch. I thank God that old engine was able to clear the jammed gears and restart and get me to an airport.

I don't blame Rotax at all; that old engine ran sweetly and perfectly for nearly 1000 hours, until human error caused its demise. Still lovin the Rotax 912.

[ken nougaret]

Correct on the tail support. These springs were just trick to help support my tail. Attach BEFORE folding the wings.

[Kitfox Pilot]

Oh wow Jim I bet that was a heart stopper, on top of a engine stopping then looking down at a river landing being the best option.
I'm glad it turned out the way it did with no crash scene.

Thanks for taking the time to share this story and best of all your starting over with that new engine!