Learjet Winter 1999

• Accessory Shop News
• Silhouette Headliner STC
• Starter Reconditioning Can Save Money
• Do You Know Your Oil Type & Oil Change Interval?

Accessory Shop News

Duncan’s Accessory Shop has developed an FAA approved repair for Bendix voltage regulators (P/N 2680014-X), used on the model 30 and 50 series aircraft. This repair significantly reduces the problems with generator splits caused by failure of the paralleling circuit. Additionally, the repair reduces the costs incurred by the customer as a result of this type failure.

Duncan’s Accessory Shop has also developed an FAA approved repair for the Hydraulic Pump (p/n 6600301-3), used on the model 30 and 50 series aircraft. This repair significantly reduces the cost of a typical overhaul.

For more information, contact Skip Laney or Chris Gress in LNK at 800.2284277 or Pete Kilmartin in BTL at 800.525.2376.

Silhouette Headliner STC

Duncan has received an STC for a one-piece composite silhouette headliner upgrade for Lear 30 series aircraft. Subsequent installations will be certified under this STC. The headliner upgrade will be available as a kit by mid-1999.

Currently, the headliner has been installed in six aircraft with a seventh in process.

For more information, contact Skip Laney or Steve Elofson in LNK at 800.228.4277 or Pete Kilmartin in BTL at 800.525.2376.

Starter Reconditioning Can Save Money

Duncan’s Accessory shop has been working with Lear 30/50 series operators to develop a reconditioning program for the Lear/Bendix starter 6608268-6. Our research on starter premature armature failures indicates a commutator and brush reconditioning program will extend the life of your armature and brushes. Duncan believes that reconditioning the armature commutator and re-seating and re-run in 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 break down (mica is an electrical insulation between the armature commutator bars). This mica break down is non-reversable 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. For more information, please contact Chris Gress or Skip Laney in LNK at 800.228.4277 or Pete Kilmartin in BTL at 800.525.2376.

Do You Know Your Oil Type & Oil Change Interval?

TFE731 engines that have incorporated ceramic No. 4 & No. 5 seal runners per Service Bulletins TFE731-72-3596, TFE731-72-3597, or TFE731-72- 5111, are now required to use Mobil 254 oil when servicing the oil system. In addition, the Mobil 254 oil must be changed at an interval not to exceed 450 +/- 50 hours.

Following incorporation of the above referenced service bulletin, there were 16 failures of ceramic seal runners, all on engines using oils other than Mobil 254. It was determined that accumulated coke from the oil came into contact with the ceramic seal runners causing the runners to fail.

Mobil 254 oil has shown less tendency to form coke than any of the other previously approved oils. If oil other than Mobil 254 has been, or is currently being used, the oil must be replaced with Mobil 254. Service Information Letter F73 l-89 gives the pertinent details of the requirements and procedures to be followed to comply with this requirement.

For more info about this development, please contact Cecil Sloan or Jon Dodson in Lincoln at 800.228.4277 or Dan Arrick in Battle Creek at 800.525.2376.

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