4 MUST-HAVES FOR PT6A ENGINE LINE MAINTENANCE
Certain equipment is essential for keeping a PT6A engine running smoothly. Here are four tools and parts that either the aircraft owner or the operator needs to have when doing routine maintenance work.
1. FUEL NOZZLE FLOW CHECK AND PRESSURE CHECK FIXTURES
Typically, ultrasonic fuel nozzle cleaning should be carried out every 200 to 400 hours(1) of flying time, to make sure the nozzle is performing properly and there are no problems such as blockages. "Whenever you clean your fuel nozzle, you should also check it for leaks and flow irregularities like drooling, spitting, streaking or other patterns that could damage the hot section," explains Yves Houde, PT6A Customer Manager at Pratt & Whitney Canada.
Checking for irregularities of the fuel nozzle requires the use of both a flow check fixture and a pressure check fixture. These are fitted over the nozzle to help identify tips that need to be cleaned or replaced and verify the presence of any leaks before the aircraft is returned to service. Learn more about what to check for in our article on fuel nozzle maintenance.
2. BORESCOPE KIT
Whenever undertaking fuel nozzle maintenance, make sure to perform a borescope inspection at the same time. To do this, you will need a borescope kit, including a guide tube for accessing hard-to-reach areas of the engine. Using a borescope is much easier than the old-fashioned method, which involves opening up the engine.
A borescope allows for assessment of hot section components for wear or damage that may not be evident from a regular ground power check or flight data collection. For instance, on a single power turbine engine, inserting a borescope through the exhaust duct port and power turbine stage may reveal trailing edge cracks on compressor turbine blades.
“It’s the number-one equipment you need to have for line maintenance,” says Yves. "The time when fuel nozzle cleaning is performed is an ideal moment for operators to assess the hot section's condition with a borescope. We also advise using it to check the first-stage compressor for foreign object damage every year.”
Borescope kits are made by a number of companies. PT6A owners can check their engine’s maintenance manual for the recommended product’s part number and order it from a designated supplier.
It's hard to generalize about PT6A engines, but there's some equipment you can't do without. It's the core of the line maintenance you need to perform.
3. OIL FILTER PULLER/PUSHER TOOL
Oil filter maintenance is recommended every 100 hours or so. When doing this procedure, use a puller/pusher to open and close the filter’s check valve. While the oil filter can be popped out by hand, it’s not a good idea to do so, since it could damage the oil filter check valve seal, which in turn could lead to static oil leak when the engine is not running.
4. TURBINE RINSE TUBE AND COMPRESSOR WASH RIG
PT6A engines may need to be washed periodically to remove salt and other impurities; how often depends on the operating environment. Whenever it’s time to clean the engine, a compressor wash rig and turbine rinse tube are essential.
Unlike other engines, most PT6A engines already have a wash ring installed around the air intake, so all you need to do is connect the compressor wash rig and insert the water. After the compressor wash, use the turbine rinse tube to clean the turbine as well.
You don’t need any special cleaning solution for a desalination wash—pure, ionized water will do. "But it’s always a good idea to test the water quality first to make sure it's suitable for cleaning," adds Yves. "If you use the wrong water, washing may end up causing more problems than it solves." Have a look at our article on desalination washes for more tips on keeping your engine free of contaminants.
(1) Refer to your Engine Maintenance Manual (EMM), Periodic Inspection Fuel Nozzle Cleaning interval for the interval that applies to your engine model.