Archive for August, 2013

Oil analyses: An IO-470 speaks

Thursday, August 29th, 2013

As I’ve mentioned before, the sweepstakes Debonair had a major overhaul completed in 2007, at Penn Yan Aero. Penn Yan does great work, but the then-owners didn’t fly the airplane much for the next five years. In that period of time they put approximately 28 hours per year on the airplane. Those hours most probably were local flights for currency purposes.

That’s not much time. For much of those five years it was tied down–outside–on a ramp at Hartford’s Brainard Airport. So the oil level sank to the sank to the sump in the crankcase, leaving the camshaft, pistons, valve assembly, wrist pins–the whole top end, in other words, left high, dry, and free of a proective oil coating. Well, maybe it wasn’t exactly dry up there. Condensation must have occurred as humidities and temperatures rose and fell, and the seasons came and went. Obviously, this promotes rust.

Since taking delivery of the airplane, I’ve logged about 36 hours in N75YR’s left seat, on trips to Minnesota (D’Shannon Aviation, for tip tanks, window, and gap seal installation); Kansas; New Mexico (Santa Fe Aero Services, for avionics install); Lakeland (for display at Sun N’ Fun); Newburgh, New York (KD Aviation’s paint shop); Oshkosh (for display at EAA AirVenture); and Batavia, Ohio (for Air Mod’s interior renovation).

In other words, the airplane went from torpor to serious flying. Right before Oshkosh, we had an oil change done, and an oil analysis performed by Blackstone labs at the same time. The numbers–especially for iron–were disturbingly high. Iron particles in the oil represent wear from the cylinders. Aluminum (top end components), chrome (camshaft lobes), copper (bearings and valve guides), and silicon (dirt) were also represented in elevated levels. The high lead readings are from the lead in avgas, and aren’t cause for concern. Blackstone called us to express their interest in the engine’s condition.

A meeting of the minds–Penn Yan and Blackstone–came out with a recommendation to keep flying the airplane, but to change the oil at more frequent intervals. Compressions have been good, by the way, and the engine runs smoothly, puts out rated power, and meets book performance.

This is what happens when a long-still engine comes to life. Deposits work free as moving surfaces are cleaned by fresh oil, and acids and water are eliminated by long periods of combustion.

After Oshkosh, Air Mod changed the oil. It had been seven hours since it was last changed. We were hoping to see lowered particulate levels–and we did! Here is theBlackstone report, showing the results of the two analyses:

Blackstone's oil analysis from the oil changes made on July 23 and August 12.

Blackstone’s oil analysis from the oil changes made on July 23 and August 12.

So now the plan is to keep flying (look for more cross-country flying in the coming months) and keep quick-changing the oil. We’re also installing an Airwolf spin-on oil filter (the IO-470 has a screen, not a proper oil filter) so that we can better examine the filter for particles. The filter could also help capture any older particles that have been trapped over the years. In effect, we’re flushing the engine’s oil free of contaminants. We hope.

“If I sat on a couch for five years, then got up and went to New Mexico and back, I’d be shaking loose some deposits of my own,” said Bonanza/Debonair guru Adrian Eichorn. Well put. I’ll show the next oil analysis results when the time comes. If the numbers go down, great. If they don’t, we may have to consider another overhaul–an unplanned alternative we hope to avoid.

 

OK, who made the tail strike?

Tuesday, August 27th, 2013

As Air Mod continued its extensive belly-cleaning, work progressed toward the tailcone. Under all the gunk and dirt of the ages a surprise was uncovered. At some point in the airplane’s history there was a tail strike. The impact occured right on the tail’s tiedown ring, but left no sign of damage there. During the prebuy inspection a slight indentation was noted near the tiedown ring, so there was some suspicion of a tail strike. (But no evidence of any structural damage to the aft bulkhead supporting the tail structure. Good thing, that. Damage in this area would have been a very big deal indeed.)

Once the tailcone was made shiny-clean, the situation was plain. There had indeed been a tail strike, and of such force that it cracked a support bracket. Wow. Air Mod called some purveyors of vintage aircraft parts (a/k/a junkyards, er, salvage yards) and these brackets are apparently as scarce as hen’s teeth. Even so, hopes are high that we’ll eventually find one.

But let’s think about this. How could this have happened? The answer is obvious, of course. Either one of 75YR’s previous owners WAY over-rotated on takeoff, or WAY over-flared on a landing. Either way, the conditions must have been desperate for this to cause the damage we see here:

Wham-o! First off, look at how clean the internal skins are, now that Air Mod has cleaned them. But the cleaning revealed a crack in a support bracket. Meanwhile, only slight indentations in the skin tell of the tail strike.

Wham-o! First off, look at how clean the internal skins are, now that Air Mod has cleaned them. But the cleaning revealed a crack in a support bracket’s right side. Meanwhile, indentations in the tailcone skin tell of the tail strike.

The Debonair’s tail rides high as it sits on the ramp, so any rotating or flaring had to be on the violent side. Perhaps the pilot encountered a big downdraft on short final, and made a mighty effort to soften the ensuing landing/arrival? Or maybe a short runway and high density altitude encouraged an over-enthusiastic takeoff?

Whatever the reason, we’ll address the damage as part of the interior work package. Ah, those 50-year-old airplanes….the stories they could tell!

 

Air Mod takes on the interior

Thursday, August 22nd, 2013
AOPA's Sweepstakes Debonair, on Air Mod's ramp

AOPA’s Sweepstakes Debonair, on Air Mod’s ramp

Look for an upcoming article in the October AOPA Pilot, but thought I’d show you some of the work now going on at Air Mod. Air Mod, located at the Clermont (Ohio) County Airport in Batavia, Ohio, does more than simply pull an old interior and replace it with a newer one. The company also puts a lot of effort into dealing with corrosion and hidden problems. “This airplane is pretty typical of the older airplanes we work on,” said Air Mod president Dennis Wolter. “It’s got rotting floorboards and about an inch of dirt all along its belly.”

The interior was an aftermarket replacement for the original. Features include no lumbar support and now-rotting carpet and sidewalls. Take a good look, because it's history--already.

The interior was an aftermarket replacement for the original. Features include no lumbar support and now-rotting carpet and sidewalls. Take a good look, because it’s history–already.

Wolter and his crew will spend about 80 hours just cleaning up this mess, the detritus of 50 years. A tarry substance–an asphalt-based goo that Beech used as a corrosion preventive–has attracted dirt over the years.  It will take days of work to remove it and inspect the bare aluminum below for signs of corrosion. So far, the news is good on this front–no untreatable corrosion. But the dirt is daunting, and hard to reach. Wolter uses lacquer thinner and lots of ScotchBrite pads to make the interior skins shiny again. After that, the skins will be chromated, and ready for years of corrosion-free service.

The belly of the beast. Here you get a good look at the asphalt, plus the static line for the pitot-static system. The tube ends should have been secured with hose clamps. Soon, they will be.

The belly of the beast. Here you get a good look at the asphalt, plus the static line for the pitot-static system. The tube ends should have been secured with hose clamps. Soon, they will be.

Dirt, old springs, washers, and much more fell to the belly of the 50-year-old Debonair

Dirt, old springs, washers, and much more fell to the belly of the 50-year-old Debonair

“I weighed it, just for kicks,” said Wolter of all the dirt. “It’s four pounds.”

Of course, the interior is now completely gutted, and the seats are bare skeletons, awaiting cleaning, corrosion treatment, and new, leather-covered cushions with headrests. The seats will feature a dark-gray leather design, the sidewalls and headliner will be white leather with Bubinga-wood trim, and the carpet will be dark blue.

The old headliner--here secured with duct tape--will soon go. The fresh air scoop is opened and closed using a headliner-mounted control and it will be lubricated for smoother operation.

The old headliner–here secured with duct tape–will soon go. The fresh air scoop is opened and closed using a headliner-mounted control and it will be lubricated for smoother operation.

Best of all: the old seat belts will go. They’ll be replaced with four-point harnesses up front. The shoulder restraints are from BAS Inc. so many thanks to them. I hated flying with just a seat belt.

So adios, old interior! You were lovingly installed by a previous owner, but your glory days are done. And it had that moldy, Florida-damp smell, too. I once took something out of a saggy old pouch that was hung on the door. The pouch came off in my hand. Another time, I was getting a chart out of a side pocket. The chart snagged on a corner of the pocket, and r-r-r-i-i-i-p-p! There went a huge swath of that old brown sidewall. That looked ugly, so I pulled some more, and it was actually kind of fun pulling the sidewall free. It was so effortless! It was so…. rotten!

A glimpse of the near future: Swatches showing elements of Air Mod's interior scheme.

A glimpse of the near future: Swatches showing elements of Air Mod’s interior scheme.

As always, more news to follow, so stay tuned…..