Category Archives: aircraft engine maintenance

Fashionably Late Doesn’t Apply To Your Engine TBO. Here’s Why

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

There are two simple reasons why always respecting an engine’s TBO is of fundamental importance to any operator: performance and economics. Discover why this is one deadline you don’t want to miss.

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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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King Airs and Caravans Serve Special Mission Needs

When it comes to special mission aircraft, Textron Aviation has a deep lineup of airplanes suited to the task, ranging from the single-engine piston Cessna 172 to its most sophisticated Citation jets. But its most popular mission-oriented aircraft come in two turboprop types, the Caravan single-engine and the twin-engine King Air series. Both product lines are prime examples of dual-purposing, with a large following in the civil market for everything from owner-flown transport to commercial charter and business aviation flight departments. But these aircraft, when equipped for specific non-commercial or military operations, show their true mettle.

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Canadians set to rock “Thunder Over Louisville” with R-1340 North American Harvard Trainers

On April 18, the Canadian Harvard Aerobatic Team (CHAT) wrapped up several weeks of spring training and is heading south for the coming “Thunder Over Louisville” airshow.

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The History & Story of the R-985 Powered Boeing PT-17 Stearman

Climbing over the narrow, wing-root walkway and stepping on to the cushioned seat of the tandem, two-place, blue and yellow fabric-covered open-cockpit Boeing PT-17 Stearman registered N55171 in Stow, Massachusetts, I lowered myself into position with the aid of the two upper wing trailing edge hand grips and fastened the olive-green waist and shoulder harnesses.  Donning era-prerequisite goggles and helmet, I surveyed the fully duplicated instrumentation before me and prepared myself both for an aerial sightseeing fight of Massachusetts and a brief, although temporary, return to World War II primary flight training skies.

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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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Radial Engine Time Between Overhaul: What’s My TBO for the R-985 & R-1340?

 

Please allow me to offer some information in regard to Pratt & Whitney R-1340 & R-985 engine Time Before Overhaul intervals (TBO’s) for engines utilized on current agricultural aircraft. A letter from Pratt & Whitney (P&W) faxed to the Federal Aviation Administration (F.A.A.) dated February 13, 1990 is useful in understanding the organization’s corporate position on the radial engine.

AT-302
Ayres AT-301 Air Tractors VH-ODB and VH-ODM at Tintinara SA in May 1989
Designed by Leland P. Snow, the AT-302 designation indicates 320 gallon hopper and P&W R-1340 radial engine
From http://www.goodall.com.au/photographs/aerial-agriculture-80-1/80saerialag-1.html

“Pratt & Whitney have no company or F.A.A approved methods for providing any engineering substantiation or manual/publication revision relating to new methods or procedures which are being accomplished by operators and overhaul shops on Pratt & Whitney reciprocating engines.”

This letter establishes a, “hands off” attitude on P&W’s part concerning the Reciprocating Radial engines. Oil consumption is a major issue and is addressed in a cautionary statement constituting part of the P&W TBO considerations given in the R-1340 & R-985 overhaul manual (part number 123440).

“Oil consumption is usually one of the best indications as to whether or not the engine requires overhaul, provided the engine is performing normally and there is no indication of possible trouble or irregularities requiring more than normal line maintenance attention. A sudden increase of oil consumption or a gradual increase of oil consumption to double that which has previously been average, is usually case for overhaul.”

The engine’s primary accessories (Carburetor, Fuel pump, Magnetos, Starter, Propeller Governor, and Generator) are designed to run to engine TBO. It is our recommendation that they be overhauled at the same TSO as the engine. Ref: AC65-12A Chapter 10 Page 411 Par. Major Overhaul Our basic TBO recommendations are 1000 to 1400 hours operating time since overhaul. In order to determine this “recommended” Time Before Overhaul we have taken into consideration all forms of Agricultural utilization of the R-1340 & R-985 engine and have averaged the operating time between overhauls of engines submitted to us for overhaul over the last 25 years.

Weatherly 620A VH-WEA
Manufactuered in 1989, Weatherly 620A VH-WEA is powered by a 9-cylinder, Pratt & Whitney R-985 radial engine however the aircraft itself has a relatively low spraying capacity of 1200 litres. From http://airqueensland.blogspot.com/2015/01/r-mach-aviation_7.html

It must be noted that there is an Airworthiness Directive 68-09-01 issued to the R-985 engine. It is concerning Crankshaft flyweights and flyweight liner replacement. This AD mandates that it be accomplished at 1200 or 1600 hrs depending on propeller installation. In order to accomplish this, the engine must be disassembled to the point it is more economically feasible to overhaul than to limit to repair and replacement only. This Time Before Overhaul recommendation is made with the assumption that all manufacturers’ recommended/required periodic inspections are complied with in a timely manner throughout the life of the engine. This recommendation is not to certify or guarantee that an operator will achieve a specific number of hours operation time before an overhaul is necessary. This TBO recommendation should in no way be considered a maximum TBO limit as it is possible to safely operate an R-1340 & R-985 past 1200 or 1400 hours TSO. It is merely a RECOMMENDATION that, hopefully, will better enable an operator to develop a safe, economic engine overhaul schedule.

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