Learjet Summer 2000

• Maintain Tire Pressure
• Lear Buying Opportunity?
• TAWS Mandate
• Bleed-Air Valve Improvement STC (Mod Valve)

Maintain Tire Pressure

In the last revision of the Learjet 35 Maintenance Manual, Chapter 20 Section 12-10-05 tire servicing procedures were changed. The tire pressures have remained the same but there has been a table added that recommends tires be removed from service if they are found to be 90% below recommended service pressure. If a main tire is found to be 80% below recommended service pressure, the manual recommends replacing that tire, as well as the adjoining tire on that strut.

Remember that cold tire pressure should be 100 to 105% of specified service pressure. This information is not in all the Learjet Maintenance Manuals yet, but we feel it will be included in the next revision. Ref: MM-99 Rev. 68 Feb. 11/00.

For info, contact Bill Schroeder in LNK at 800.228.4277 or contact Pete Kilmartin in BTL at 800.525.2376.

Lear Buying Opportunity?

In the last six months, Lear inventories have increased as follows:

• 35/35A—65>87 (+34%)
• 31/31A—17>29 (+71%)
• 55—15>17 (+13%)
• 60—4>8 (+100%)

Increasing numbers may lead to downward pressure on prices.

For details, call Duncan’s Aircraft Marketing Services at 800.228.4277.

TAWS Mandate

In a final rule dated March 29, 2000, the FAA has mandated that Terrain Avoidance Warning Systems be installed on all turbine powered aircraft carrying six or more passengers. The compliance date is March 29, 2005. The FAA estimates this mandate will affect more than 18,000 turboprop and turbojet aircraft. The math indicates that avionic shops throughout the nation will be overwhelmed with these installations. Duncan Aviation advises that operators plan and comply early to avoid a huge last minute rush. By planning and complying early, you also get the added safety benefit in the meantime.

There are two manufacturers that have a product that will meet this requirement (TSO C151a), the Honeywell (Previously known as AlliedSignal/Bendix/King) Enhanced Ground Proximity System and the Universal Avionics TAWS units.

For more information, please contact Ron Hall in LNK at 800.228.4277 or contact Dennis DeCook in BTL at 800.525.2376.

Bleed-Air Valve Improvement STC (Mod Valve)

As a result of the failure factors of heat and pressure deterioration of the gaskets and “o”-rings, as well as sediment and debris contamination of the various control orifices on the primary HP regulating section of the bleed-air valves, Duncan Aviation developed a STC modification for the 50 and 30 series aircraft to increase valve reliability.

Since the above mentioned deterioration factors begin to effect valve operation on average between 150 and 300 flight hours time in service, the bleed-air system modification greatly improves the valve service life and reliability. Of course, the aircraft’s maintainability is improved, reducing downtime. From a resale stand point, the value of the aircraft is enhanced as a result of the incorporation of the bleedair system improvement.

Due to these improvements, the modified valves last much longer and include a two-year warranty. Many of the modified valves have been in service for more than four years. For more information, please contact Chris Gress in LNK at 800.228.4277 or contact Pete Kilmartin in BTL at 800.525.2376.

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