AOPA's Win a Six in '06 Sweepstakes - Engine Headaches and Milestones

November 11, 2009

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February 23
Engine Headaches and Milestones

Got parts? As the Win A Six winds up the powerplant phase of its restoration, that question keeps popping up. As anyone who has maintained an older airplane is well aware, finding parts for a 40-year-old airplane can be a real challenge. Most manufacturers simply stop feeding the supply chain for airplanes that old. With parts out of stock, that means manufacturers have to custom-fabricate them from scratch - on an expensive, one-at-a-time basis. They have to verify the part number, look for long-dormant engineering drawings, find the tooling and jigs needed to make the part, then get busy at the workbench. No wonder parts cost so much.

We weren't surprised to encounter a parts availability problem when we set out to restore this year's Cherokee Six-260. Baffling availability seemed to be the biggest problem, and I wrote about this issue in the last sweeps Web update. The old baffling was bent, cracked, and repeatedly welded over the years in valiant attempts to preserve their utility. Because tight baffling is so important to directing a proper airflow through air-cooled engines, engine cooling can suffer if baffling fits poorly or has cracks or other irregularities. Besides, we want the engine compartment to look better than new, so new baffling was a priority.

But we weren't expecting the search for one particular part to be so daunting. That part is the induction air box. Piper part number 65402-002, to be exact. (Not that I've committed that number to memory or anything). Anybody out there seen one lately?

The air box, like the baffling, is made of thin aluminum. As the name implies, it's shaped like a box and has holes and fittings in it to accommodate the induction air filter, carburetor, and carburetor heat duct. The box has a number of bends and angles in its construction, and over the years vibrations and other stresses can cause the box to crack and weaken. Sort of like baffling.

You can weld the aluminum to repair an air box, but welding aluminum is tricky. The metal is so thin, and its granular structure so conducive to crystallization when subjected to the heat of welding, that you only get a couple shots at fixing or patching it. Then you can't weld it any more without making the box so weak that it may collapse under stress. As in: the stress of ram air entering it at 120-plus knots.

So it was with our air box. A call from Ultimate Engines sounded the alarm. Ultimate's Dena Johnson broke the news. She tried to be tactful - "There's a problem with the air box. It's been welded too much" - but there was no mistaking the gravity of the situation. The air box was shot. Ultimate repaired the original air box, but this will only be a stopgap measure. A new one had to be found. But where?

Salvage yards were called. No luck. The Piper Flyer Association's experts were consulted. They're still searching. A call to The New Piper Aircraft, Inc. brought the most reassurance. As you recall, New Piper had plenty of baffling in stock for that crisis. And the parts that they didn't have in stock they built. Then they shipped them overnight to Ultimate. Could they do the same with a new air box?

New Piper's Lisa Geissert and Matt Burvic got right on it. First they checked the stock room. No air boxes for the 260-hp Lycoming O-540 in our Cherokee Six. Did they have the tooling to make a new one? Yes, but that might take a week, and we're on a tight schedule. How about the parts stashed away in New Piper's maintenance network in the field?

Bingo. At this writing, Burvic says he's found a spanking-new air box at a New Piper dealership - in Germany. If all works well, the new air box will be winging its way across the Atlantic in short order. The system works! Thanks Lisa and Matt!

Hanging it up
The other big news is documented in the photos accompanying this writeup - and in the photo gallery posted on this Web site.

Drum roll, please.... The overhauled engine is back in one piece and is now hanging on the newly refurbished engine mounts, which in turn are hanging on the newly detailed firewall. As you can see, the engine looks great. To top off its like-new appearance, the engine block was painted blue - to match the airframe's paint scheme. And hey, check out that shiny new baffling!

The propeller - also featured in the photo gallery - is soon to be installed on the engine, and as soon as the new air box is installed the next milestone is set to take place.

That would be the first engine runs. First, Ultimate will start the engine and check for any leaks or other problems. Then it's time for a few test flights to document engine parameters (manifold pressure, propeller performance, engine temperatures). After that, it's my turn to take the Six to Vero Beach, Florida, where LoPresti Speed Merchants will install a racy new cowling, a one-piece windshield, a bunch of speed mods, and a "Boom Beam" xenon landing light.

Check back next week for more photos of the final engine work - and videos of those first engine runs! After four months in the engine shop, I can hardly wait to see the new and improved engine in action. And see how that three-blade prop and Designer Prop paint job looks up front.

—Thomas A. Horne

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