COMMANDER TIPS: Nose Gear Spacer Action – After Incident

A recent field report regarding the nose gear spacer has prompted Twin Commander to generate a Recommended Maintenance Action on the nose gear spacer, part number 750080-1. The incident appears to be a result of improper torqueing of the castellated nut, leading to a failure of the roll pin. This Maintenance Recommendation will help to ensure no future issues arise from this condition.

All models except the 520 and 560 serial numbers 151 through 190 are affected. It is recommended the check must be completed as soon as possible, and during every annual/150 hour inspection thereafter. The procedures are as follows:

1. Insert a 1/32-inch or a number 67 drill bit or equivalent through the roll pin to
   clear out any foreign material.
   1. If the drill bit goes through, slide a length of 0.025 safety wire through
      the roll pin as shown in figure 1. Secure the safety wire as shown.

      Figure 1. Roll pin integrity checked and safety wired.

   2. If the bit does not go through the roll pin, try using a smaller drill bit
      or a length of .025 safety wire. If the safety wire goes through, follow the directions in
      #1a.
   3. If the .025 wire will not go through the roll pin, the spacer should be
      removed and replaced before operating the aircraft. Remove and replace the spacer per the applicable
      Maintenance Manual instructions. Turn the castellated nut on the stud until it bottoms out against
      the washer. Do not tighten nut any more than is necessary to line up the next opening of the nut
      with the cotter pin hole in the stud. Once the new spacer is installed, follow the directions in
      1a.

      Note: Overtightening can shear the roll pin.

2. At every 150 hour/annual inspection, check the safety wire to ensure it is still present and intact. If the wire
   is missing or broken, follow the steps in 1a through 1c.

Twin Commander Aircraft has redesigned a version of the spacer that does not require a roll pin. Once this version is available and installed it will no longer be necessary to perform the Maintenance Recommendation. Parts will be available as a Custom Kit in the first quarter of the year. The company is also considering issuing a Service Bulletin that incorporates this procedure.