Photos and Commentary

Resolving Mysteries

Jan. 8 — Sometimes it's nice not to know what's going on inside your engine. Keeps you from being a nervous wreck just thinking about all that metal thrashing around in there. Then again, what you don't know might just put you in hot water.

So it was with this year's AOPA Sweepstakes airplane — a 1965 Piper Twin Comanche that's all set up for a complete overhaul and refurbishment. If you haven't already read about our initial adventures with the original, unvarnished airplane (the story is in the February issue of AOPA Pilot magazine), then let me briefly cover the highlights.

Off with the old....	Technicians at Williams Airmotive reskin the Twin Comanche's stabilator.

Associate editor Steve Ells and I found our/your Twin Comanche in Salinas, California, then flew it across the country to LoPresti Speed Merchants in Vero Beach, Florida. Along the way it was evident that several things weren't quite right with the engines. For example, they weren't very smooth, they loved burning oil, the props wouldn't stay synched up, and at full power the engines only turned up to 2,500 rpm. They should have been cranking away at 2,700 rpm.

The folks at LoPresti — who are installing all their speed mods, J. L. Osborne wingtip fuel tanks, and making airframe repairs as we speak — sent our sick powerplants to wintry Penn Yan Aero for complete overhauls. They'll come out of the process as Superior Air Parts' Millenium engines. These newly overhauled engines should be finished by the end of the month. The Millenium engines have fully through-hardened steel cylinder barrels, dynamically balanced internal components, and are built to conform to closer tolerances than the originals. Superior has been at the forefront of aircraft piston engine overhaul technology for years, and we're more than happy to have them aboard as participants.

Especially since Penn Yan's Bill Middlebrook called to give an update on the overhaul's progress. "What did you see inside the old engines?" I asked. (Here comes the "what you don't want to know" angle).

"Oh, it was worn out," came the answer. This turned out to be an understatement. The crankshaft and camshaft lobes were worn down well past specifications, the valve guides were leaking oil, the chromed cylinders were allowing oil past the piston rings (this confirmed the wisdom of going with the Superior's stronger, hardened-steel cylinder barrels) and, and, "oh, we found a chunk of aluminum inside one engine's case, about the size of a pencil eraser," Middlebrook announced. Somehow, part of the case's innards had been flopping around amidst the rotating crankshaft, bearings, and connecting rods since who-knows-when. And, of course, all during our three-day odyssey to LoPresti's.

Talk about ignorance being bliss! If I had known that, I would have left the airplane in California.

Anyway, all's well that ends well, and for the new engines the wellness program is progressing. Superior's Millenium engines carry a five-year warranty and use a lost-casting process — not the traditional sand casting — in making the cylinders. Superior says this minimizes cracking, lets the cylinders dissipate heat more efficiently, and makes them stronger and smoother-looking than the bad old engines of just a few weeks ago.

Tiffin Aire of Tiffin, Ohio, is hard at work overhauling our old prop governors and propellers, so the waaah, waaah, wa-wa-wa-wa-ing that plagued our trip east should be distant memories.

On the airframe side, we can't say enough about the high-quality work being performed by Williams Airmotive. Williams is reskinning the Twin Comanche's dinged-up, hangar-rashed, ailerons, flaps, and stabilator, and they have done it in record time. The stabilator in particular can be a trouble spot in Comanches and Twin Comanches. Patching of dings and stop-drilling of cracks is a no-no according to Piper service documents, so reskinning of the entire stabilator is the only acceptable method of repair. Then the stabilator-as with other control surfaces-must be carefully balanced after painting in order to avoid dangerous flutter in various speed and loading regimes.

Williams is also on the prowl for a new cabin door. Our current door doesn't fit to our liking, so the answer might be a new door. "Piper tailor-made and -fit each Twin Comanche with its own matching door, so finding a perfect match can be a hassle," said Roy Williams. "But we'll do what we can to scare up a winner."

Fine by me. Anything to avoid the noise Ells and I endured on our San Luis Obispo-to-Florida trip. Then, duct tape came to the rescue. Now there's the promise of a bona fide fix...and we can put the duct tape back in the tool box!

Stay tuned to this same channel in a few more weeks. I'll have more updates here and every month in AOPA Pilot — and hopefully much milder adventures — to keep you posted on your born-again, classic Twin Comanche.

In one year, it could be yours!