November 11, 2009
By Marc E. Cook
For the first part of its stay with us, the Millennium Mooney was in the hands of Top Gun Aviation in Stockton, California, for a thorough inspection of the airframe and a few (very few) modifications. The shop is run by father-and-son team Tom and Mark Rouch. While a number of the other large Mooney shops also work the modification angle heavily (and thereï¿½s nothing wrong with that) Top Gun specializes in maintenance proper. It is highly regarded in the Mooney community. Tom makes the point that he never has to advertise yet his schedule book is always full. Call it word of mouth doing the legwork.
Our 1987 201 came to Top Gun with a recently completed annual and in generally good condition. But the Top Gun guys are known as sticklers so weï¿½re not surprised they found a host of small problems.
The one that worried us most was a rough mag check, with excessive rpm drop and a noticeable loss of power in flight. With 1,600 hours total time since new, the Lycoming IO-360 is well along toward the 1,800-hour TBO, so word of reduced power is not terribly welcome. They tore into the Bendix dual mag and found the internal timing off on one sideï¿½itï¿½s easy to have the drive gears slip during assembly and have one set of distributor blocks one tooth offï¿½and the entire mag slightly off-timing as well. The D-2000 mag is original to the engine. Most mag specialists advise 500-hour service intervals for this mag and an upgrade to the D-3000 at overhaul time. Weï¿½d do more with it, but weï¿½re expecting to replace the engine later this summer and ultimately fit electronic ignition.
Similarly, the spark plugs were all fouled and, perhaps a contributing factor, Top Gun found the idle mixture on the Bendix fuel injection was set too rich.
Otherwise, the engine was fine, with good compressions, nothing untoward in the oil filter, and the usual minor (and annoying) oil leaks of a high-timer. According to most mechanics, the 200-horsepower IO-360 is among the most reliable aviation engines, with fewer valve and guide problems than the parallel-valve models and generally robust construction. That is has just four cylinders to the Continental IO-360ï¿½s six also helps keep maintenance costs down. (That said, a few items like the Lycomingï¿½s sodium-filled exhaust valves are dramatically more expensive than the comparable Continental parts.)
While prowling around in the engine compartment, the Top Gun staff discovered a number of small sheetmetal problems that deserved immediate attention. For example, one cowl-flap hinge was broken, and there were cracks in the lower cowl-mount flange.
Airframe-wise, the Millennium Mooney turned out to be clean and complete. A handful of minor problems were tackled, like a broken hose on the vacuum-operated Precise Flight speed brakes and a variety of control-system issues. Various rod-ends were out of spec; nothing unusual for an airplane of this vintage if somewhat unexpected given the total time. At least the airplane few a decent number of hours per yearï¿½123, to be exactï¿½during its life. As is typical, though, these hours were put on in fits and starts.
Top Gun removed the entire interior of the airplane and inspected the Mooneyï¿½s distinctive steel-tube cage; the techs found no corrosion.
One last item on the pre-project squawk list was to replace the shock discs. Mooneys use rubber biscuits instead of hydro-pneumatic struts and, over time, these biscuits deteriorate and become compacted. As a result, the airplane tends to sit nose-up on the ground. Top Gun replaced all discs in just three hoursï¿½thatï¿½s why you pay a little more to go to a Mooney-specific shop. The discs themselves were less than $400.
On to the modifications, then. So far, they total just three. 1) New windows from LP Aeroplastics; 2) a Boom Beam high-intensity-discharge landing light from LoPresti Speed Merchants, and 3) wingtip recognition lights from Mooney. The recognition lights slot into the existing sculpted wingtips easily; the kit costs $550 from Mooney. The LP Aero windows cost about $1100 total and consumed some 38 hours of labor. If that sounds excessive, youï¿½ve never seen the job done. It involved a lot of sheetmetal work and a tremendous amount of tedious trimmingï¿½regardless of whose windows you useï¿½and excruciating care to mount and seal properly. The Top Gun guys do this all the time and have lots of special tricks to make the job go smoothly.
Finally, the Boom Beam. LoPresti sells the whole kit for more than $800. You may say to yourself, thatï¿½s a lot of standard landing lights, and youï¿½d be right. But LoPresti is selling the Boom Beam on two, desirable conceptsï¿½that the HID light is much brighter than the standard sealed-beam unit and far, far more durable. Itï¿½s probably the latter characteristic that will sway buyers. We havenï¿½t used the light at nightï¿½yetï¿½and will be sure to give it a workout during the Mooneyï¿½s stay with us. Weï¿½ll let you know how the light fares.
Finished with the airplane, Top Gun sent the Millennium Mooney along to Pacific Coast Avionics in Aurora, Oregon, where a comprehensive avionics remake will take place. Thatï¿½s for next time.
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