Nov. 18 — The Win-A-Twin Comanche got a great reception at AOPA Expo in Long Beach, and hundreds of visitors had a chance to see it up close and personal. How enthusiastic were the gawkers? Well, we're still getting the occasional request for advance notification of the winner's identity (so that the requestee can contact the winner with a cash offer). Sorry, but we're not in the brokerage business; you'll just have to wait until February or so to find out who won.

Windshield leaks
After Expo, I flew the Win-A-Twin to the Livermore Municipal Airport near San Francisco, where it stayed for a few days. The weather dawned gray for the day of my departure for the trip back to Frederick, Maryland. The ceiling was 1,000 overcast with light rain, and the visibility was five miles.

Ever since mid-October California had been getting an early taste of winter weather. A series of cold fronts — one of them particularly vigorous, with icing at the 5,000-foot level — had blown through from north to south. And one more was causing the weather for my departure. A look at the radar display in the airport terminal showed much heavier rain to the south of Livermore, along my route past the Panoche, Priest, and Avenal VORs.

The departure was uneventful, and it was very satisfying indeed to follow the Garmin GNS 480's commands during the departure procedure. The WSI InFlight datalink weather showed Nexrad imagery on the Garmin MX 20's display, but now it contained some bits of yellow contouring near Panoche. Sure enough, after 10 minutes or so, the rain picked up and became what I would call moderate in intensity.

Ordinarily this wouldn't be a problem. Yes, the rain was noisy, but the Bose X headsets took care of that. Outside air temperatures were in the plus-5 degree Celsius range, so icing wasn't on the menu.

But some windshield leaks were. From a couple of screw fittings came a steady drip, drip, drip of rainwater. During heavier rainfall, those drips became more like trickles. Good thing I had some paper towels to quickly soak up the leaks.

By the Palmdale VOR in southern California, the rain and clouds were things of the past, and for the rest of the trip east, there was no precipitation — or weather of any real significance — to speak of. Quite unlike the trip west to Expo, I had tailwinds and smooth rides. The first stop was at El Paso, the second at Memphis, and the third was Frederick.

But now there's another item on the squawk list. We'll be taking a conservative approach to the windshield leaks, and it will involve replacing the existing windshield with a new one — mainly because two small cracks were detected emanating from a couple of screw fittings along the upper edge of the windshield. Apparently some screws had been overtorqued during an installation procedure. And, of course, new sealant will be applied. At this point it looks like KD Aviation will do the work at its Stewart International Airport location in Newburgh, New York. We're most grateful to LP Aero Plastics, which will be supplying the second windshield, as they did the first.

Wonky fuel gauges
Oh, there's another repair item, too. We thought the fuel gauge errors were fixed, but the gremlins are back. When the main tanks are brimming full, the airplane's fuel gauges read empty. When the aux tanks are empty, the gauges read half-full. Ditto the tip tanks.

Twin Comanches have two fuel gauges — one for the left wing, one for the right. When you switch fuel tanks, the fuel selectors engage one of three microswitches (they're under the floor, accessible through the fuel drain trap door), each corresponding to a fuel tank. The idea is for the gauges to indicate the fuel levels in the selected tanks. So much for theory.

Evidently the microswitches are out of adjustment, and this has to be addressed. Webco Aircraft — one of the big parts suppliers for the Win-A-Twin project — thinks it's the switches (not the sending units in the fuel tanks) that are the problem, because if you wiggle the fuel selectors, the gauge indications go to reasonably accurate indications.

All the more reason to trust your own calculations when it comes to fuel burns in this or any other general aviation airplane. Yes, the JP Instruments EDM-760 engine analyzer/fuel totalizer is extremely accurate and provides all sorts of fuel-related information. But it carries a placard warning not to use it for fuel information.

Even when "fixed," light general aviation aircraft fuel gauges can be notoriously inaccurate. Same thing with the Win-A-Twin, and we'll be sure to educate the winner about the airplane's fuel system — and its two indicating systems as well.

WAAS-ready
A visit to Frederick Aviation's avionics shop gave the Win-A-Twin an upgraded GPS/Navcom. Though the nameplate on the faceplate still says "CNX 80," the unit is technically a GNS 480. The upgrade gives the receiver the ability to fly WAAS (Wide Area Augmentation System) approaches. WAAS uses a network of ground stations to boost GPS signal accuracy, and it's this accuracy that allows instrument approaches (some with vertical guidance) to more and more airports around the United States. See the next issue of AOPA Pilot for a feature on flying WAAS approaches. By the time you read this, I'll have hopefully flown a few WAAS approaches in the Win-A-Twin and will report on the experience as well. One of the first WAAS approaches to have been certified was to Frederick Municipal Airport — AOPA's home field — so finding a nearby WAAS approach should not be a problem.

To earn IFR certification for the WAAS upgrade, I had to test the GNS 480 by putting it through its paces. The test checklist included intercepting and tracking courses, checking track errors, executing holding patterns, flying instrument approaches, and making sure that the autopilot (a Meggitt/S-Tec System Fifty-Five X) inputs and outputs are correct. All went well, and the official paperwork should be finalized in a couple of weeks.

On the test flight with me was AOPA's executive vice president of Communications, Jeff Myers. It was his first ride in the Win-A-Twin, and the first Frederick-based AOPA staffer (other than me) to fly in the fully refurbished airplane. I have a hunch we may be flying together again — on the delivery flight to the winner's airport, sometime in February. — Thomas A. Horne