Learjet 35/55: Prevent Premature Starter Armature Failures

June 2013

Technicians in the Duncan Aviation Accessories shop, recommend a reconditioning program for the Lear/Bendix starter 6608268-6 on Learjet 35/55 aircraft. Our experience has taught us that a commutator and brush reconditioning program will extend the life of your armature and brushes. The reconditioning of the armature commutator and re-seating and re-run on the brushes every 800 hours (maximum) will divert armature commutator damage.

In cases where the armature commutator and brushes are not reconditioned, the commutator will become pitted and burnt from the diminishing electrical connection to the eroded brushes. This armature commutator damage will progress to the point of mica electrical breakdown (mica is an electrical insulation between the armature commutator bars). This mica breakdown is non-reversible in most cases, and the armature must be replaced.

A common symptom that this is occurring would be the engine is slow to spool at engine start.