Category Archives: PT6A Engine

The PT6A-50 Powered De Havilland Canada DASH-7

During the 1950s and 1960s, the aircraft manufacturer De Havilland Canada (DHC) acquired extensive experience in the construction of small and medium capacity transports with short takeoff & landing (STOL) capabilities, such as the “Otter”, “Twin Otter”, “Caribou”, and “Buffalo”. In the early 1970s, DHC decided to create a four-engine turboprop medium STOL airliner, which emerged as the “DHC-7” AKA “DASH-7”. The DASH-7 was only built in modest numbers, though it did prove useful as a military surveillance platform. DHC followed it with a twin-turboprop airliner, the “DHC-8” AKA “DASH-8”, which proved much more successful. This document provides a history and description of the DASH-7 and DASH-8.

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4 Must-Haves For PT6A Engine Line Maintenance

This article originally appeared on the P&WC Airtime Blog.

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.

YVES HOUDE

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.

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The Douglas DC-3: 81 Years and Going Strong

The Douglas DC-3 Doesn’t Know the Meaning of the Word “Quit”

The same year the German airship Hindenburg crossed the Atlantic, the still-flying-today Douglas DC-3 was introduced to the world. The DC-3 is widely viewed as one of the most significant transport aircraft in history, due to its massive and long-lasting impact on the airline industry, and aerospace engineering. I got the chance to interview Ric Hallquist, the retired Chief DC-3 Pilot for Missionary Flights International who flew and worked on the beefy twin engine transport plane for over 30 years.

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Maintenance Repair & Overhaul: Another Approach To Monitoring PT6A Engine Health?

High-tech sensors and systems may not be the only way to monitor engine health. Pratt & Whitney Canada has embarked on a project called Oil Analysis Technology, applying it first to the PT6A engine. But Program Manager Frederique Richard says the approach may have much wider applications.

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The PT6A – The Legend Tells Its Story

THE PT6 ENGINE MILESTONES

It’s the remarkable story of a remarkable engine. With more than 51,000 engines delivered to power some 130 different applications, the PT6 engine can tell quite a story of creativity and transformation. While we had a lot to choose from, we’ve put together a list of milestones for the engine as we mark its golden anniversary.

This is a great #PT6A animation showing how all the components move inside the legendary #turbineengine.

A video posted by Covington Aircraft (@covingtonaircraft) on

1957 – P&WC assembled a team of 12 talented young engineers after studies showed a market opportunity for 500 shp (shaft horsepower) class turboprop engines in the aircraft market then powered by piston engines. P&WC saw an opportunity to channel some of the profits from its piston engine spare parts business towards the development of gas turbine engines smaller than those made by its U.S. parent.

Twelve key men on the PT6 engine design team: Gordon Hardy, Jim Rankin, Fernand Desrochers, Fred Glasspoole, Ken Elsworth, Allan Newland, Pete Peterson, Hugh Langshur, Jean-Pierre Beauregard, Elvie Smith, Dick Guthrie and Thor Stephenson.

Twelve key men on the PT6 engine design team: Gordon Hardy, Jim Rankin, Fernand Desrochers, Fred Glasspoole, Ken Elsworth, Allan Newland, Pete Peterson, Hugh Langshur, Jean-Pierre Beauregard, Elvie Smith, Dick Guthrie and Thor Stephenson. © Library and Archives Canada. Reproduced with the permission of Library and Archives Canada. Source: Library and Archives Canada/Credit: Bruce Moss/Weekend Magazine collection/PA-167966.

1963 – It’s what our celebration is all about. In December 1963, P&WC shipped the first PT6 production engine, the PT6A-6, to Beech Aircraft Company for its Beech 87, which later became the King Air. The PT6A-6 was a highly innovative gas turbine that represented a significant advance in technology from the traditional piston-driven engines used to power small aircraft.  Gas turbines have a higher power to weight ratio than piston engines.

The first PT6 production engine.

The first PT6 production engine. P&WC Archives (Records and Information Management).

1967 – Piper’s PA-31 Navajo took its first flight powered by PT6A-20s. Piper had enjoyed enormous success building light aircraft since the 1930s, but it took P&WC years of effort to get Piper to adopt turbine engines and move away from their traditional reliance on piston-driven engines.

1968 – P&WC’s ST6L73 engine (a derivative of the PT6A without the gearbox second stage) entered into service as an auxiliary power unit (APU) for the Lockheed L1011 airliner.

1968 – Bell Helicopter placed its initial order for P&WC’s first turboshaft, the PT6T Twin-Pac® engine

1970 – P&WC’s PT6T Twin Pac® entered into service. It is two engines coupled in a single package to power medium-sized, twin-engine helicopters.

1970 – The United States Military ordered 294 Bell 212s under the designation UH-1N equipped with PT6T Twin-Pac® turboshaft engines. Delivery also began in 1970.

1973 – The second-stage power turbine was introduced on the PT6A-41. This was a step change in engine power and efficiency.

1979 – An Air Tractor agricultural aircraft is powered by a PT6A engine and flies to the National Agricultural Aviation Association convention in Las Vegas – the first time such a combination was displayed in public.

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