Tuesday, July 28, 2015

Matco Answers Questions At Oshkosh

Much like a moth is attracted to flame, once again I found myself being drawn to the Mecca of experimental aviation … Oshkosh. As the moth, I did get a tad burned from catching a little too much sun while walking around AirVenture for a handful of days. As always, had a great time at the show and the weather was about as good as it gets.

One of the last tasks performed on the DOG Aviation RV-12 prior to leaving for Oshkosh was installing the landing gear and the Matco axles. As mentioned in the posting two posts prior, reading Matcos’ instillation manual for the wheels and brakes raised a few questions. While at AirVenture, I was able to track down Matco and received answers to a few of the questions I had regarding the instructions for the Matco wheel and brakes supplied in the RV-12 finishing kit from Van’s Aircraft.

I asked about the lubrication page at the back of the instruction manual calling for the use of an anti-seize lubricant on the wheel bolt threads … yet that was not mentioned in the assembly instructions. The answer: At one time different components were used that benefited from use of anti-seize lubricant. The anti-seize lubricant is no longer required … the lubricant list at the end of the manual has not been updated to reflect this change.

Other question regarded the Matco manual mentioning to check the clearance between the disc and brake pad, but offers no guidance on how to make the adjustment. The answer: Matco adjusts the brake caliper to the brake disc clearance at the factory using the Matco axle. Because the RV-12 uses both a Matco wheel/brake assembly and the Matco axle, no adjustment is necessary.  The adjustment only comes into play when using a third party axle with the Matco wheel/brake assembly.

The third and final question posed to Matco regarded the torque value specified for the two AN4 bolts that go through the caliper and secure the inboard brake pad. The torque is listed at 100 inch pounds which is double the 50 inch pound (low end value) for an AN4 bolt. The Answer: Because the caliper bolts at this location utilize Nord-Lock washers, a much higher torque value is necessary to overcome the drag imposed by the Nord-Lock washers as the bolts are tightened. The resulting torque on these bolts is within the specifications for an AN4 bolt.