Matt Throckmorton's ("DocThrock") Team Rocket F1 EVO Kit Plane Construction PagesTeam Rocket F1 Engine Tear Down Page Last Modified:
On This Page: Dismount, Open and test components of wrecked F1 Rocket TMX-IO-540
On June 12, 2009 I had to make a forced landing in my F1 EVO. Regrettably, on roll out the plane flipped in the mud and it pretty much totalled the airframe. In hopes that I could rebuild my Rocket, I began determining whether or not the engine was salvageable. Since the engine is the most expensive single component on the airframe, it was very important to determine whether the engine was going to need a simple tear down inspection, some level of repairs, or whether the engine was scrap just like the airframe. I came to the conclusion that if the engine could not be returned to service economically, I would just take the insurance money and buy a different plane.
I made a bid on the salvage after my insurance company and adjuster determined my Rocket was in deed totalled. My salvage bid was accepted. As soon as I knew I was going to keep the engine (for testing at least), I began to investigate whether or not the engine was worth repairing and inspecting. An email from Mattituck, who made the engine, was very discouraging and said the engine was probably catastrophically damaged. That may be the case.
The first thing we did was dial in the crank. It turns out that the crank flange is no more than .002 out, and the center barrel appears to be completely unharmed. A replacement crankshaft is about $10K. Making sure it's at least straight where the prop bolts on (since the composite prop blades were completely destroyed), without cracking open the case was very important. Jeff Wellum, race engine builder and pilot buddy) brought his dial indicator and we measured according to the Lycoming overhaul manual and found the crank well withing specs. That's not unusual, and wasn't unexpected. When you have a composite (read: wood covered with plastic) prop, when the blades shear, the crank and it's end drive components don't usually take that much force. Unlike a metal prop, a composite or wood prop comes apart pretty easily.
That't not to say we're out of the woods. The engine had a catastrophic oil line failure and loss of engine oil. The engine did not seize, and the prop was certainly turrning (maybe even under some residual power) when we nosed over in the mud, then cartwheeled onto our backs. But the engine wasn't making sufficient power to keep us in the air long enough to get us to an airport.
The issue with the loss of thrust (not so much losing engine power) may be due to the fact that the propeller loses oil quickly, and my aerobatic counterweighted prop went full coarse pitch. It's kind of like being feathered, and the blades revert to a perpendicular direction with respect to the direction of travel. The blades end up just fanning air as the engine turns, not creating thrust. The blades essentially just get out of the way of the airstream as much as possible and greatly increase your glide distance.
On of the first things I noticed about the engine was that I could not get compression in all cylinders using a differential compression tester. I removed the bottom plugs and noted the first cylinder I checked still had great compression. But the second piston, even at Top Dead Center would not compress. Not good.
After checking the crankshaft flange for "run out", and checking for compression, we next opened a mag cover in the accessory case. When I was pulling the prop stubs over, I could not get most of the cylinders to compress. We pulled a rocker cover off of #1 and found out that the valves were not moving. Uh Oh. Inspection through the back of the accessory case told the story. There is a drive gear bolted and pinned to the rear end of the crank shaft. That gear drives the accessories and the cams. You can see up inside the left mag hole that the gear at the end of the crankshaft does not turn when you pull the prop through. All the other gears appear fine. The crankshaft MAY be able to be repaired. IF the cranshaft end where the gear is bolted and pinned on is not galled more than .006, they can probably put a new gear on and recertify the crank. The dowel pin that lines up the crank and the gear also has to be replaced. If there is a wallered hole where the pin sheared off, you can put in an oversized dowel pin up to a point. But if the pin hole is too big, or the crank is galled, then the crank is toast, and this rebuild project is over.
On to phase two. We have to get the crank out to see if it's workable. In the mean time, we also might as well have a look at the pistons, cylinders and everything else along the way. So it's time to disassemble the engine cylinders and many accessories and remove the engine from the mounts.
John Watler and I pulled one of the cylinders. It's pretty easy.
We looked inside the barrel and noticed it looked beautiful. No gouging.
Piston looked pretty good too. There's some question about the carbon and some scaring at the hot end of the piston. Going to have to ask someone more knowledgeable about aircraft engines about that.
So John and I went ahead and pulled the rest of the jugs off and carefully set them aside, keeping all the parts for each cylinder together, particularly the push rods. The engine is starting to look a little naked. That's quite a spaghetti mess on top. I'll clean that up by myself later.
After John left, I decided to go ahead and continue to take the engine apart. I removed most of the components on top and under the engine. Then I got out my "cherry picker" and removed the engine mount bolts.
Next thing I need to do is figure out whether to buy an engine stand or just rig something to support the crank as we pull everything apart.
Forgot my good camera in my car.... These are phone pics.....
I pulled the sump off the bottom of the engine. There was no metal in the oil/water combo laying in the base of the sump. None.
I hoisted the engine over a barrel just in case the hoist slipped. Sometimes they get slow hydraulic leaks.
It was easy to remove the accessory case from the back this way.
When Watler and I pulled off the accessory case (easy), all the gears stayed in place (the engine was tipped slightly nose down.
There are two large gears (one has an idler cam that drives the mechanical fuel pump). Between the two large gears you see is a smaller gear. That is the gear on the back of the crankshaft. It is threaded into the crank. It is locked by a metal tab that you bend over the bolt and the gear. The bolt was about 5 threads out, and the retainer clip was loose. I snapped the bolt off getting it out. The bolt was VERY bent.
You see two posts sticking out with a disc between them. That is the rear face of the crank. There is an eccentric dowel pin that aligns the gear with the crankshaft. That pin was sheared right at the crank face.
Neither the bolt, the pin or the gear scratched the crank. If a machine shop can back out the broken bolt, I think the crank can be fixed.
Brought the gear and bolt home to take close up pictures. The bolt head is about where it was sitting inside the oil pump drive spline. Fortunately (or not, depending on how you look at it), the bolt is the softest part of the conglomeration of parts. You can see that as the bolt BACKED OUT, it's head got pounded around. That bent the bolt. But it didn't appear to affect the crank gear or the oil pump drive. That retainer clip was loose, also, btw.
This picture doesn't really give you the full impression of just how bent the bolt is. But you can see the end of it.... see how it was twisted off. Yep, a good chunk of the bolt is still stuck in the crankshaft. The teeth on ALL the gears are just as pretty as they can be and show virtually no wear or damage.
The picture below shows the bottom face of the drive gear that sits on the rear face of the crankshaft. You can see the alignment hole that is normally occupied by the dowel pin. The chunk of pin was still sitting in the hole. It snapped off as cleanly as you could ask for.
The next thing to was get ready to split the case and get the crank out of there. I still needed a stand to work with. I decided to use a 2"x10"x4' board, drill it for the prop flange and bolt the two together. I left the hoist hooked to the ears just in case....
Then I took pictures all around the case, then removed all the fasteners. I thought the bolts with the safety wired castle nuts in the sump area were particularly pretty!!!
Now I either need to do the "Fred Flinstone" method ( i.e. mallet and wedges) or find the "Lycoming tool" to bolt to the through bolts and drive the halves apart. I may have to try to find one of those tools at OSH.
John Watler coaxed his buddy Dan Gunder in to lending us a "Lycoming case splitter tool", We started using it last night and realized that one of the bolts was stripped. Looks like it had been nutted up off kelter. Anyway, only 7 of the 8 bolts were usable. John, being the resourceful guy that he is, made a replacement at work.
One plate bolts up on the fixed studs on one end of the engine.
The other plate goes on the fixed studs at the other end on the other side of the engine. The idea is to push the through studs out the other side.
We started cranking away using the 1 1/8 box end wrenches. We tried to keep the plates and nuts even. It just didn't seem to work that way for some reason.
We kept at it trying to figure out why the project was so hard....
The accessory case end wouldn't crack open because we didn't remove a hiddle castle nut that was safetied to a through stud behind the cam gear.
John had the bright idea to use a Lycoming base wrench to loosen the nut. It worked, but we had to start it one tooth at a time.
Once the case opened beyond the retaining studs, we safetied the cam to the left side and laid the engine on it's right side (just like the OH manual sez).
We lifeted the left half of the case off. The bushings (main crank bearings) stayed where they were supposed to, no reaching in to catch them. The from main bearings still had so much fresh oil (like most of the rest of the engine) that they stayed on the crank.
The left side looked pretty as a picture, clean as a whistle, fresh as a daisy....
The bearing surfaces look pretty damn good to all of us.
Everything looks great....
I took a couple pics to reference how the main bearing/bushings go (not exactly sure about the correct name...).
Match up the holes side to side. Seems pretty straight forward... .like most of this engine....
The only thing we saw that we DIDN'T like was some corrosion on ONE lobe of the cam. Looks like rust that's been there a while.
Next step, lift out the crank with the rods in tact and ship it (and maybe the cam) to Aircraft Speciaty Services.
8/9/09 I was going to box up and ship my crank, cam and related parts, but got a wild hair and decided to drive them to Tulsa. Bruce Dallman, who resides in Pittsburg Kansas invited me to stay at his house overnight since he lives only 2 hours from Tulsa. Sunday night we had a nice steak dinner and a great little visit. Bruce also looked over my engine parts and found a crack in the accessory drive gear that came off the back of the crank. He also assessed the rust on the cam (minor and repairable in his opinion) as well as the broken bolt and dowel in the crank (somewhat difficult but very do-able).
8/10/09 Off to Tulsa. A beautiful morning for a drive. Aircraft Specialties Services is next to the international airport and two doors down from the engine case repair shop called DIVCO. ASS is an old conglomeraton of a few small buildings, kinda run down. Inside, the place is organized, almost overflowing, and well worn. Everyone was quite nice and eager to help. I saw one old computer in the shop. The company apparently doesn't do email, which I found rather archaic. However, I think these guys are too busy getting parts from A&Ps and turning them around to fast to even mess with email. I could sort of understand how emails with them wouldn't be that helpful, and might slow them down tremendously. I gave my parts and information to Randy, and they dropped them in line for diagnosis and repair. Randy kind of looked at me funny when he noticed my license plates were from Indiana and I told him I drove down. I was there about 15 minutes, then off for the 8+ hour drive home.
8/11/09 Call from Tina at ASS asking for permission for them to grind my cam. Corrosion on two lobes. $15 if the grind fails (pitting too deep) or $135 if successful for a 6 cylinder camshaft. I told her to go for it.
8/12/09 Call from Bob at ASS. Seems the crank is OK dimensionally, and he agreed there was no damage from the bolt/gear on the aft face of the crankshaft. He said the first attempt to remove the broken bolt failed and that a different technician would try another technique. He said they had removed several similar broken bolts. I told him that if they didn't feel comfortable removing the bolt, to send it back to me and I'd have a different machine shop remove it. Bob ended the conversation by wishing me good luck and he'd advise me of their status.
8/15/09 No return calls on the status of any parts since Tuesday. I did get a one page letter from ASS stating the part and serial numbers from everything I left with them. That inculded the crankshaft with the rods attached (they didn't particularly like that) and the counterweights, the camshaft, and the two large "magneto gear" that turned off the crank drive gear. Standing by....
8/19/09 Call from Tina. My cam was not able to be salvaged. The corrosion (read:rust) pits were through the hardened layer, so the cam is scrap. Dimensionally it was fine, though. She said they were still working on the crankshaft, however she did not know what they were doing with it (gone to lunch when she called). The rods are evidently fine, so that's good. So far, the good news is that everything is dimensionally OK. That's encouraging. Still, have to wait for word on the "TEN THOUSAND DOLLAR BOLT".