TFE731 Spring 2004

• Rise in ITT - Operational Check Surge Bleed Valve
• N1 DEECs Approved for Westwind/Astra

Rise in ITT - Operational Check Surge Bleed Valve

— Honeywell

Have you seen your engine ITT increasing, or does your JetCare report show a recent trend of an ITT increase? The surge bleed valve could be causing this problem. The following procedure is an excerpt of the Light Maintenance Manual referencing how to operationally check the surge bleed valve. Please refer to your applicable Light Maintenance Manual for the specifics to your engine.

1. Perform normal engine start in accordance with Aircraft Flight Manual (AFM) and/or appropriate aircraft document.
2. Switch EEC/DEEC to manual mode with cockpit switch. CAUTION: DO NOT EXCEED ENGINE OPERATING LIMITS
3. With EEC/DEEC in manual mode, slowly advance power lever to takeoff power N1 specified in AFM and/or appropriate aircraft document, maximum N2, or maximum ITT limit, whichever occurs first. With power lever in this position, allow engine to stabilize for approximately three minutes. Record N1 and ITT from cockpit indicators.
4. Retard power lever to idle and return EEC/DEEC to normal mode with cockpit switch. NOTE: When performing the following step, ITT should normally peak early during stabilization, then decrease slightly. If ITT again rises after stabilization,V the surge bleed valve poppet may be creeping open. If this occurs, perform Surge Valve Inspection in accordance with Inspection/Check.
5. With EEC in normal mode, slowly advance power lever to obtain the same N1 recorded in Step 3). With power lever at this position, allow engine to stabilize for approximately three minutes. Record N1 and ITT from cockpit indicators.
6. Retard power lever to idle and perform normal engine shutdown. NOTE: On a cold day, the delta ITT will normally be on the low side of the range specified in the following step, and on the high side on a hot day.
7. If ITT recorded in Step 3) is not approximately 15 to 30 degrees C. (27 to 54 degrees F.) higher than ITT recorded in Step 5), perform Surge Bleed Valve and Solonoid Controller Checks specified in your applicable Light Maintenance Manual.

The TFE731 experts at Duncan Aviation can assist you through this process. For help at any time, please contact our TFE731 Technical Representatives:

• Battle Creek: Ken Kuchenreuther 800.525.2376
• Lincoln: Lanny Renshaw 800.228.4277

N1 DEECs Approved for Westwind/Astra

— Mike Healzer

The Supplemental Type Certificate (STC) ST1855CH-D for installation of N1 DEECs on IAI 1124/1124A/1125 model airplanes is now available. The STC can be accessed at Honeywell’s website, www.e-engines.honeywell. com. The download includes authorization to use the STC to install N1 DEECs on IAI 1124/1124A Westwind and 1125 Astra airplanes.

The Learjet 55, JetStar II, and Sabreliner are the remaining airplanes to have N1 DEECs approved.

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