BY PRATT & WHITNEY CUSTOMER SERVICE
September 12, 2018 | Diagnostics, PT6A, Turboprops
P&WC’s connector care guidelines help optimize dispatch availability by preventing electronic engine control faults. That’s why they have been adopted as standard maintenance practices by customers such as Bombardier and QantasLink.
1. APPLY CONTACT ENHANCER TO CONNECTORS
Electronic engine control (EEC) systems are an increasingly popular option among operators of P&WC engines. These systems are extremely precise and reliable, but once in a while, a fault may be reported. Whether it’s a non-critical fault that doesn’t affect dispatch availability or a critical fault requiring immediate attention, the cause often lies with a connector in the engine and airframe electrical wiring harness.
As André Gallant, Training Specialist, Field Support Office, explains, there are various reasons why a poor connection may occur: excess vibration could cause a connector to come loose, for instance, or moisture infiltration could lead to oxidation.
No matter whether you’re flying a fixed-wing aircraft or a helicopter, if you’re using electronic engine control, good connector care at the interval specified in the manual is important. Faults are rare to begin with, but you can make them even less likely by following some simple steps.
ANDRÉ GALLANT, TRAINING SPECIALIST, FIELD SUPPORT OFFICE
One basic tip is to apply contact enhancer to the connector pins and sockets, which will help to enhance their conductivity and maintain a reliable connection. P&WC recommends Stabilant 22, an off-the-shelf product that’s widely available. It has been found to increase the reliability of pin-socket contact up to ten-fold. “
This serves a dual purpose,” notes André. “Not only does it enhance contact, but by filling up the space between the pins and sockets, it prevents moisture from getting inside. You don't need to use a lot of contact enhancer—just a small amount to wet each pin and socket should be enough."
As with other parts of the engine, moisture from the operating environment is a concern for connectors. The infiltration of humidity may oxidize the pins and impede performance.
2. PERFORM ALL STEPS IN THE CLEANING PROCESS \
Before re-connecting a connector, it should be cleaned thoroughly. As explained in detail in the engine maintenance manual, this is a multi-step procedure involving tasks such as rinsing the connector with alcohol, applying contact cleaner (deoxidizer) and so forth. André stresses that each step is important and none of them should be skipped. Otherwise, the fault may not be resolved, or it could recur again soon.
The purpose of cleaning is not just to remove fluids like oil and water by rinsing the connector—it’s also to remove oxidation. If you don’t perform cleaning properly, there may still be some oxidation remaining. That’s why it’s essential to go through all the steps specified in the manual, even if you’re in a rush.
ANDRÉ GALLANT, TRAINING SPECIALIST, FIELD SUPPORT OFFICE
3. TIGHTEN THE CONNECTOR PROPERLY AFTERWARD
When re-attaching the connector after cleaning and maintenance, always follow the maintenance manual procedure carefully. One step in particular is easy to overlook but should always be carried out: applying a counter-load to the backshell while torqueing the connector ring using soft-jawed pliers or a mini-strap wrench. This ensures it’s as tight as possible and less likely to come loose accidentally.
André has trained thousands of people on connector care over the years. “Many of them were not aware of the importance of applying a counter-clockwise load to the backshell,” he remarks. “Whenever I demonstrate the difference, students are always amazed at how hard it is to loosen the connector afterward.”
4. COVER UP THE CONNECTOR WITH INSULATION TAPE
Finally, as an insurance measure, André also recommends putting electrical insulation tape over the connector after it has been properly cleaned and tightened. Much like the contact enhancer inside, this kills two birds with one stone: it insulates the connector from atmospheric moisture while also preventing it from coming loose.
Not all faults are the result of a poor connection; it could be an issue with the engine sensors or the harness instead, such as a cut wire. Follow the steps indicated in the engine maintenance manual for a given fault in order to isolate its cause, then proceed with the recommended troubleshooting measures.
There is a video about connector care, tailored for the PW100 engine family, available on the MyP&WC Power customer portal. You can locate it simply by typing “connector” in the portal’s search box.
Connector care is also part of our recommendations for auxiliary power unit (APU) maintenance. Learn more in our article on APU maintenance dos and don’ts.