AD 76-02-07 ACTIVE

76-02-07 PRESTOLITE: Amendment 39-2500. Applies to Prestolite ALV-9400 through ALV-9410 series gear driven alternators.

For aircraft having Prestolite ALV-9400 through ALV-9410 series alternators with more than 100 hours time in service compliance is required within the next 25 hours time in service after the effective date of this AD unless already accomplished within the last 75 hours time in service, and thereafter at intervals not to exceed 100 hours time in service from the last check.

To detect defective alternator slip ring end bearings and minimize the probability of in-service failures, accomplish the following:

Remove the slip ring end bearing cover by using a small sharp chisel, knife blade, or screwdriver to pry it out of the alternator slip ring head. Care must be taken not to damage the end head or bearing cover. If the bearing cover is damaged during removal it must be replaced.

Without further disassembly visually inspect the bearing and shaftend for discoloration or any sign of overheating or wear. Pay particular attention to the bearing inner and outer race.

If there is any sign of overheating or an indication that the rotor shaft has been turning in the inner race or the outer race has been turning in the end head, the alternator must be removed and repaired.

If the rotor shaft has been turning in the bearing inner race, the rotor and bearing must be replaced. If the bearing outer race has been turning in the end head, the bearing and end head must be replaced.

Check the bearing grease for any sign of overheating or contamination such as dirt, or metal filings. If the grease is a dark brown or black color, or is so contaminated, the alternator must be removed and the bearing replaced.

If the bearing shows no sign of discoloration, overheating, wear, or contamination, the bearing only (not the entire cavity) should be filled with Chevron BRB#2 or Chevron SRI#2 grease or an equivalent approved by Chief, Engineering and Manufacturing Branch, Great Lakes Region. At this time we are not aware of an equivalent lubricant for this application.

NOTE: Refer to Continental Service Bulletin No. TCM M75-30 for further information concerning this subject. The checks required by this AD may be performed by the pilot.

Operators who have not kept records of hours time in service on individual alternators shall substitute aircraft hours time in service in lieu thereof.

This amendment becomes effective February 2, 1976.