JT15D Engines Spring 2003

• Engine Spooling
• Service Where You Need It
• Troubleshooting Oil Pressure Problems

Engine Spooling

— Joe Austin

If you are spooling an engine with the intention of not starting it, be sure to allow the engine to spool to at least 10% N2 before pushing the disengage button. This procedure will help the large contact relays last longer. The large current draw that is flowing through the contacts of the relay drops as the engine increases in speed. Quick cycling of the start relays can cause them to weld together even when the "START DISENGAGE" button is pressed. If this happens, your only course of action is to disconnect the battery from the system using the green Elcon connector at the battery. Be sure that the throttle lever(s) are in the cut-off position. This check is required during a phase 5 inspection, but we have had calls from operators doing it for other reasons.

For additional information, contact Ken Kuchenreuther in BTL at 800.525.2376.

Service Where You Need It

— Tim Garity

If you find yourself in the middle of nowhere and your airplane needs service, don't feel helpless. Dial 877.522.0111 to reach Duncan's Rapid Response Hot Line. For engine or airframe support, you're just minutes away from technical help, or a few hours from having technicians arrive at your location to get you back in the air again. Service is available 24/7, 365 days a year, for nearly all types of corporate aircraft.

Troubleshooting Oil Pressure Problems

— Dan Arrick

We receive a few calls throughout the year regarding oil pressure problems on JT15D-powered aircraft. The oil pressure system on the JT15D is very reliable and normally trouble free, but occasionally there are discrepancies that require some troubleshooting. Here are some basic steps to help you troubleshoot some common oil pressure problems. Remember to always refer to the appropriate Pratt & Whitney or aircraft manufacturer's maintenance manual for procedures.

1. Always check the engine oil level per maintenance manual recommendations. Low oil levels can cause fluctuations and increase oil temperatures.
2. Inspect the oil filter. Plugged or partially plugged filters can cause low oil pressure. If the filter is plugged, be sure to determine what is plugging the filter and take appropriate corrective actions.
3. Determine the oil pressure indication system is OK. This can be accomplished by running the system with an external calibrated pressure source such as a Dead Weight Tester. Apply pressure to the oil pressure transmitter and read the gauge in the cockpit to ensure indication credibility.
4. Inspect and clean the Oil Pressure Relief Valve if necessary. Sometimes these valves can stick causing pressure fluctuations. These fluctuations are most notable in flight and appear as a reduction in oil pressure as the aircraft climbs to altitude.
5. Check the oil pump part number. In older pumps, the oil pressure tends to follow throttle movement and indicates low at idle.

For additional information or free technical advice any time, contact Dan Arrick or Ken Kuchenreuther in BTL at 800.525.2376.

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