By Don Maxwell
Published MAPA, Volume 24, Number 4
The Eight-Second Ride - SERVICE BULLETIN M20-202
G MODEL MOONEYS
Saturday morning, the weather is clear and the early morning coffee crowd, on the bench in front of the terminal, is ready to critique the landings of the local flight school.
On final approach is a modified 1966 M20E owned by Gerry Graham. Today, Terry Bewley, the owner of a 1964 M20C, is at the controls. Gerry has installed a new GPS in his panel and asked Terry to fly him around as he tries to figure it all out.
Terry and Gerry have similar aircraft ownership backgrounds. Both owned Cessna 150's before they bought their Mooney’s. Both bought their Mooney’s about the same time and both installed every commercial mod they could purchase. Their Mooney’s were also the only one’s they had flown and Terry was about to make his first landing in Gerry’s.
The coffee crowd expects nothing as the mains touch. Shortly after the nose wheel makes contact, the plane veered to the left, too much correction and across the runway to the right narrowly missing a runway light, back to the left and now it’s almost sideways. Finally, under control, they make the turnoff. As they taxi by our bench headed for the hangar, there is a lot of finger pointing and conversation in the cockpit.
After they put the plane up, they came to the terminal for their ribbing. We hear from Gerry that he was aware that his steering was overly sensitive, but he understood that “Mooney’s were like that ”and his was normal.
I assured Gerry that it was not normal and that his plane should track straight with little effort during landing.
In July of 1977 Mooney issued this service bulletin that could affect every Mooney built prior to 7-6-77. A note to the SB stated that all aircraft manufactured after 7/6/77 have been checked prior to licensing. “The purpose of this bulletins to provide instructions for checking the location of the nose wheel and instructions for adjustment of the nose gear assembly, if necessary, to locate the nose wheel in the position to obtain optimum tracking and nose gear steering during the high speed ground operations or take-offs and landings. It is recommended that this check and modification, if required, be accomplished if control difficulties have been encountered during these operations.
To check for proper tracking, place jacks under the wing. With the nose wheel on the ground, place a level, on the seam above the access door to the tail cone
Jack the aircraft up until the bubble is centered. You will notice that the main wheels are several inches above the floor and the horizontal stabilizer is nearly shoulder high.
This is a good time to stand back and look at the attitude of your plane in a level attitude. This particular plane is an early “F” model that shared the “Twist wing” with it’s big brother the Mustang.
Now you know why it’s so important to use the proper airspeed
and attitude while landing to avoid porpoising and prop strikes.
With the aircraft in this level attitude, a plumb bob,
is placed over the front of the nose gear trunnion. The plumb bob
should fall in the center of the axle. If the line falls behind
the axle, you need to add the spacer provided in the kit, and be
prepared for a pleasant experience on your next landing.
This distance should be between 9-1/2 & 10". Less than
9-1/2 and you probably need shock disc. More than 10" and you
need the SB kit.