Weak points
Posted: Tue Jul 07, 2020 7:32 pm
The Maule exhaust system is the weakest point on the airplane. Cracks in the welds are common. I've replaced or rebuilt the entire exhaust system 3 times in 22 years. Cracks are due to the way that Maule welds the pipes, thinner pipe walls and more vibration with a 4-cylinder engine. Exhaust flame traps need to be checked at each annual.
Maules do not have cowl flaps so it is difficult to control CHT and oil temperature. The engines are close-cowled and care must be taken during hot weather climbs not to overheat the cylinders. Various solutions have been explored but so far the factory does not have a cowl flaps modification.
The parking brake tabs on the pilot-side master cylinders can get gummed up and stick on one or both sides. Most Maule owners do not use the parking brake for that reason. I don't use the parking brake and I pump the brakes 3 times as part of my pre-landing checklist to make sure the tabs aren't hung-up. At each annual I clean and lubricate the tabs and the areas on top of the master cylinders.
If you have oleo gear, make sure that you replace the AN bolts at the top of the main gear legs and both ends of the oleo struts with higher-strength NAS bolts. At each annual you should have the bolts checked for rotation to make sure they aren't deformed and then lubricate the bolts.
My Maule had an inline fuse holder in the alternator field wire located about 6" from the alternator. The ring lug attached to the alternator post was crimped on the fuse holder wire and eventually broke due to the weight and movement of the fuse holder. When that happened, the alternator warning light came on and I was running purely on battery. The fix was to tie wrap the fuse holder body to a wire bundle to prevent movement and to shorten the distance from the fuse holder to the alternator to minimize wire movement. I understand that this problem was fixed in later Maules.
Although not exactly a "weak" point, I consider the yoke to be less desirable than a stick in terms of comfort and responsiveness. There are very few tail draggers with side-by-side seating in the same class as a Maule that have a stick.
Maules do not have cowl flaps so it is difficult to control CHT and oil temperature. The engines are close-cowled and care must be taken during hot weather climbs not to overheat the cylinders. Various solutions have been explored but so far the factory does not have a cowl flaps modification.
The parking brake tabs on the pilot-side master cylinders can get gummed up and stick on one or both sides. Most Maule owners do not use the parking brake for that reason. I don't use the parking brake and I pump the brakes 3 times as part of my pre-landing checklist to make sure the tabs aren't hung-up. At each annual I clean and lubricate the tabs and the areas on top of the master cylinders.
If you have oleo gear, make sure that you replace the AN bolts at the top of the main gear legs and both ends of the oleo struts with higher-strength NAS bolts. At each annual you should have the bolts checked for rotation to make sure they aren't deformed and then lubricate the bolts.
My Maule had an inline fuse holder in the alternator field wire located about 6" from the alternator. The ring lug attached to the alternator post was crimped on the fuse holder wire and eventually broke due to the weight and movement of the fuse holder. When that happened, the alternator warning light came on and I was running purely on battery. The fix was to tie wrap the fuse holder body to a wire bundle to prevent movement and to shorten the distance from the fuse holder to the alternator to minimize wire movement. I understand that this problem was fixed in later Maules.
Although not exactly a "weak" point, I consider the yoke to be less desirable than a stick in terms of comfort and responsiveness. There are very few tail draggers with side-by-side seating in the same class as a Maule that have a stick.