Friday, July 3, 2015

Trim Servo Instillation – Discover Incorrect Rivets – AD Not AK Please

The first order of business for the day was to continue work on the trim servo assembly. The Ray Allen servo is shipped with no connector on the wires so Van’s has the builder install a Micro Molex connector on the wires. This style of Molex connector is notorious for intermittent connections due, in large part, to the pins being so tiny and the wires so small that good solid crimps are not achieved (plus they are tin plated). The dust was blown off the Tool Aid crimping tool the DOG Aviation purchasing department procured a couple of years ago. Outfitted with the #18937 die the Tool Aid crimper seemingly makes a very tight crimp on the tiny Micro Molex pins and .062 Molex pins used elsewhere. In the hopes of achieving  tight crimps, each tiny wire coming from the Ray Allen servo was stripped a little long and folded back on itself prior to being inserted into the connector pin and crimped. At the first hint of an operational problem, this connector will be replaced with the gold plated pins used in DB style connectors.
Using the Tool Aid outfitted with a #18937 die to crimp the Micro Molex connector pins onto the wires from the Ray Allen servo. Note the magnifying glass ... you will need one to verify these tiny pins are crimped correctly.

One word of caution when using crimping tools with dies to crimp these tiny pins … be very careful how the pins are placed into the dies. The Micro Molex pins have TINY tangs just ahead of the area on the pin that requires crimping … if not careful it is easy to mush the tangs. In my case, the pin needed to be as far forward in the dies as possible for the tangs to clear the crimper’s dies.
Completed Micro Molex connector on wires of the Ray Allen trim servo.

Moving on, the holes in the F-1287 clevis plates were match drilled into the F-1287E pushrod. The mounting hardware for the F-1287C link and AN665 clevis tie rod terminal is to be installed to help hold the positioning of the parts while drilling.
Match drilling the #30 holes in the F-1287 clevis plates into the F-1287E pushrod.
Trim pushrod assembly drilled ,deburred and ready for riveting.

After completing the match drilling the parts are separated for deburring and reassembled for riveting. In place of the typical LP4-3 rivet Van’s instructions calls for using an AD-42H rivet. Here is where the wheels fell off. Twelve rivets were removed from the rivet bin labeled AD-42H … and as I was about to install the first rivet, noticed that it was a rivet for a countersunk hole … and these holes are not countersunk. A quick flip of the plan pages to Section 5 revealed the AD-42H rivet is NOT a countersunk rivet … the rivets in my bin labeled AD-42H are wrong. I had a total of 16 rivets in the bin and did not remember using this rivet elsewhere.  A look at the original packing list for the empennage kit reveled the bag of rivets was supposed to have 15 rivets and I had noted I had received 16. Obviously, the rivets sent long ago by Van’s in the bag were incorrect. Whoever filled that bag years ago mistakenly grabbed AK-42H rivets instead of AD-42H rivets, an easy mistake to make.  A call to Van’s has the replacement rivets in the mail … free of charge.
The incorrect rivet is on the left. The correct rivet should look just like the rivet on the right … just the next size longer.

I was a little upset that the instillation of the trim servo needs to be halted while waiting for rivets … but there are other things that can be worked on. Quite frankly, I am surprised there are not more parts errors like this, given the many thousands of small pieces that are contained in the RV-12 kits. Van’s truly does a superb job of packaging the parts but mistakes are made occasionally.

However, this brings up an important point … builders should look closely at all parts and verify that it makes sense. In my case, using a countersunk rivet in holes that were not countersunk, did not make sense.