Here at MAPA's headquarters, we get at least one call a week from someone who has spotted a wood-wing Mooney for sale at a bargain basement price (usually less than $30,000) asking us is the airplane still safe to fly or not. We thought you might be interested in what Bill Wheat has to say on this subject. For those of you that don?t know Bill, he has spent the last forty-two years at the Mooney factory in a variety of technical and engineering positions. No one knows the pre-J model airplanes like Bill. I consider him the top authority on technical matters pertaining to pre-J model airplanes, including the wood wing airplanes. Here is what Bill had to say during an interview I conducted with him recently on the subject of wood wing Mooneys.

Bob - Bill thanks for taking the time to talk to me today on the subject of wood wing Mooneys and their continued airworthiness. First of all, from your records how many wood wing airplanes were manufactured by the Mooney factory?
Bill - We built wood wing airplanes in Kerrville from 1956 thru 1960. The 150 horsepower M20 was built in '56 and '57. My records show a total of 199 M20's produced. The 180 horsepower M20A was made in '58, '59, and '60. We built a total of 499 of these airplanes before metalizing in '61. So, that makes a total of about 698 wood wing/wood tail Mooneys manufactured.

Bob - How many are still flying today?
Bill - Our records show about 350 still in airworthy condition.

Bob - Exactly how much wood was used on these airplanes?
Bill - People forget that along with the wings, the empennage was also built of wood. All M20's and M20A's were built this way originally from the factory - wood wing, wood tail.

Bob - So, why is it that most of these airplanes you see today have a metal tail?
Bill - It's because in 1968 the factory released Service Bulletin M20-170 (later revised to 170A) and the FAA released AD 68-25-6 making M20-170 mandatory. In effect, M20-170 stated "Installation of a metal empennage is mandatory within one year". As a result, most of the wood tails have long since been replaced with metal ones.

Bob - Are there still some airplanes out there flying with wood tails?
Bill - Yes, but I would consider these airplanes unairworthy. Those original wood tails just weren't meant to be flying this long. If any of your members is considering the purchase of an M20 or M20A that still has a wood tail, tell them not to buy it because of the tail.

Bob - Bill, you've flown lots of hours in the M20 and M20A. Tell me what you thought of those airplanes in their day. Also, can you tell our members why the factory decided to build the airplanes out of wood in the first place?
Bill - I have to tell you, I think that the wood wing airplanes in their day were probably some of the best airplanes we ever built in Kerrville. I know that sounds old fashioned, but let me tell you why I think that way. First of all, for equal horsepower, the wood wing airplanes were faster than the metal ones. And not just a little bit - we measured a speed loss of anywhere from 5-8 mph when we converted the wood wing M20A to the metal wing M20B. That's a lot of performance loss. The reason the wood wings were faster is simple - aerodynamics. A well built Mooney wood wing is a thing of beauty. It has a glass-like finish with almost perfect contours. The airfoil is very true and the leading edge is perfectly shaped. This results in low drag and high speed. Thus the speed difference between wood and metal.

Another factor in favor of the wood wing is the quality of the ride in turbulence. The ride of a wood wing is better than a metal one. Those of us with lots of time in wood wing Mooneys noticed right from the start that the quality of the ride in the metal wing 1961 B model was harsher and stiffer than the wood wing 1960 M20A model. Finally, the stall characteristics of the wood wing were much better than the metal ones. Because the airfoil was truer with the wood wing, the old M20 and M20A had consistent and predictable stall characteristics. Not so with the metal ones. We are always fooling around with the location of the stall strips on the leading edges of the metal wings during production flight test to get acceptable stall characteristics. With the wood wings, stall characteristics were so good that we could permanently install the stall strips into the wing leading edges while the wings were originally built and leave them there. And every wood wing stalled beautifully.

Bob - So, why did the factory want to metalize in 1961 and do you agree it was a good idea?
Bill - Absolutely, it was a good idea and the only way for the Mooney to be accepted as a modern airplane as the 1960's began. There are really three reasons why the change was made from wood to metal. And all three are good ones. First and foremost was the marketing aspect. People just believe that a metal wing will last longer than a wood one. People think of rot when they think of wood. When they think of aluminum, they think it will last forever.