Category Archives: PT6 Engine

Hot Section Inspections

Maintenance time is just ahead for many operators. Shops are starting to fill out schedules for off-season work.  One of the maintenance items that is frequently discussed is the need for an engine hot section inspection.  While hot section inspection time requirements may differ by engine model, the “mid TBO” recommendation usually applies. Performance loss can also dictate the need for an inspection.  For example, the PT6A-34AG engine TBO (Time Between Overhauls) is 4000 hours, and hot sections are recommended at 2000 hours.  For the PT6A-65AG, the basic engine TBO is 3000 hours, and the recommended hot section inspection is 1500 hours.  All this information exists for all engine models in various Pratt & Whitney Canada service bulletins.  Time constraints are listed in service bulletins, but each engine model’s maintenance manual defines the hot section inspection criteria.

What exactly is a hot section inspection?  The hot section inspection is the way of making sure the condition of some of the hardest working parts in your engine can continue to do the job up to the next inspection interval or until TBO.  The PT6 engine is all about efficiency, and the hot section inspection is a simple and fast way to confirm the engine is not losing efficiency in this extreme environment.  Because of the temperature and forces applied to the parts in the hot section, a wide variety of factors can change efficiency just through normal operation.  Fretting, wear, cracking, and rubbing all have a chance to exist in the hot section, and all can negatively affect your engine’s performance.

When the engine is split to perform the hot section inspection, one of the first tasks is to measure the compressor turbine blade tip clearance.  Tip clearance is one of the key areas for efficiency.  On a PT6A-34AG, for example, the median tip clearance is .013”.  That is only the thickness of a couple of business cards.  That clearance is awfully close for a disk that spins thousands of revolutions per minute in temperatures of hundreds of degrees. When those tip clearances begin to increase, you lose performance. In the cockpit, that means the engine is not making power because of temperature limitations.

After tip clearances are measured, the turbine disk is removed, and the rest of the hot section parts are checked for deterioration, distress, or other problems.  Once repairs are made, and issues addressed, components are resurfaced and resealed as needed.  The compressor turbine blade tip clearance is reset to get maximum efficiency by changing and/or grinding the segments.  Then the hot section is reinstalled. That is a basic overview.

There are additional requirements as part of the inspection.  Bleed valve and compressor condition must be checked.  The gas generator case has inspection criteria.  The fuel nozzles, the power turbine stator and housing, exhaust duct, oil strainers, oil filters, and chip detectors are also checked.  No one wants to invest time and money into a hot section only to find out the compressor has issues and the engine must be removed.  What if you find out that the gearboxes are making metal?  Perhaps distress in your hot section is being caused by a fuel nozzle issue?  Proper inspection of all parts and fulfilling all inspection criteria are essential when it comes to hot section inspection.

I touched on some of the things that we are doing during your hot section inspection.  Just remember it is more than a split and peak at the parts.  We want to ensure the engine is safe for the operator and can be operated to its fullest when needed.  Preventative maintenance and inspections are also a way to keep costs down.  If problems can be detected early and repaired, it is less expensive than replacing parts like a vane ring or turbine blades.

As we head into maintenance season this year, review your engine times and be sure to discuss the need for a hot section inspection.  You want to make sure once you get through the downtime, the airplane and engine are primed and ready for another successful spray season.

Please reach out to me at if you have any questions, and I’ll be glad to assist.

This article first appeared at Aerial Fire Mag here.

What is a Hot Section Inspection & Why It’s Important to PT6A Engine Longevity

The Pratt & Whitney PT6 engine has been in use since 1961 and has since logged more than 380 million flight hours, the equivalent of about 250,000 round-trips to the moon.   The most advanced PT6A engine family includes three power levels, “Small”, “Medium”, and “Large” that all have the advantage of turbine cooling, aerodynamic design, and advanced technologies in materials.  Keeping these engines running efficiently and safely wouldn’t be possible without a periodic Hot Section Inspection.

Continue reading What is a Hot Section Inspection & Why It’s Important to PT6A Engine Longevity

The PT6A – The Legend Tells Its Story


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.

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.

The P-750 XSTOL and the P&W PT6-34 Engine

Pacific Aerospace describes its flagship product, the P-750 XSTOL, as the world’s first Extremely Short Take-Off and Landing (XSTOL) aircraft and as the best in the world for the missions it was designed to accomplish. Bold claims from the New Zealand based company, to be sure, but not without foundation, as it can boast some pretty impressive performance. Much of that performance can be credited to the Pratt & Whitney PT6A-34 engine that powers the plane, but more on that in a moment.

Continue reading The P-750 XSTOL and the P&W PT6-34 Engine

PT6 turboprop engine makes General Aviation history: 50,000th engine rolls off the Pratt & Whitney Production Line

LONGUEUIL, QUEBEC, December 2, 2020 – Pratt & Whitney, a division of Raytheon Technologies Corp. (NYSE: RTX), today announced that the 50,000th PT6 turboprop engine has rolled off the production line achieving an exceptional milestone in General Aviation. With the new PT6 E-Series™ engine now in full production, powering the Pilatus PC-12 NGX, the numbers continue to grow.

“From the first application more than 50 years ago, the now-iconic PT6 engine turns possibilities into realities for our customers around the world on more than 130 different applications today,” said Irene Makris, vice president, sales and marketing at Pratt & Whitney. “With each new model of engine developed and designed for a mission, platform, and customer in mind, our employees continue to build a more efficient, smarter engine with a shrinking environmental footprint– and they continue to rise to the challenge every day.”

The PT6 turboprop engine is the proven choice for demanding, high-cycle/high-power applications in single- and twin-engine aircraft for all kinds of missions and applications. The engine fleet’s current flying population is more than 25,000 units and it has accumulated more than 410 million flight hours and counting–that’s more flying time than anyone else in this segment.

Makris sees the 50,000-engine marker as the opportunity to pause and thank customers and employees for this remarkable accomplishment. It is a testament to the ongoing success of the engine and the innovation behind its ongoing evolution. The most recent example of this being the launch of the PT6 E-Series™ engine, the first the first turbine engine in the general aviation market to offer a dual-channel integrated electronic propeller and engine control.

“This production milestone is unmatched in the industry. It offers us another opportunity to celebrate the engine’s ongoing success as we continue exploring new horizons for even more flying possibilities,” Makris said. “The achievement sits as the collective cornerstone of Pratt & Whitney in General Aviation. With the PT6 E-Series™ engine now at the forefront, we remain committed to pushing innovation as we’ve been doing since the very beginning.”

The PT6 ran for the first time in 1960, entering service in 1964. Pratt & Whitney currently offers more than 70 PT6A models, ranging from 500 SHP to over 1,900 SHP. The PT6 E-Series, the latest addition to the PT6 line, was launched in October 2019 and powers the Pilatus PC-12NGX.

About Pratt & Whitney

Pratt & Whitney, a unit of Raytheon Technologies (NYSE:RTX) is a world leader in the design, manufacture and service of aircraft and helicopter engines, and auxiliary power units. Raytheon Technologies Corporation is an aerospace and defense company that provides advanced systems and services for commercial, military and government customers worldwide. To learn more about RTX, visit its website at To receive press releases and other news directly, please sign up here.For further information: Pratt & Whitney, +1 (860) 565-9600,

pt6-a engine

Pratt & Whitney Canada Innovates Pay-Per-Hour Maintenance with the Launch of New Coverage Program

ESP®ecially for Your PT6 engine and new engine ESP plans: Enrolling today

ORLANDO, FLORIDA–(Marketwired – Oct. 27, 2016) – With more than 10,000 engines already enrolled in its pay-per-hour maintenance plans, Pratt & Whitney Canada (P&WC) is once again raising the bar with the introduction of a leading-edge Eagle Service Plan™ (ESP) maintenance program tailored to PT6A customers, as well as a major enhancement to its current ESP plan offering. Each maintenance plan optimizes aircraft availability and performance while protecting and enhancing the value of the aircraft investment. P&WC is a subsidiary of United Technologies Corp. (NYSE:UTX).

The ESP plan is a simple, cost-effective pay-per-hour engine coverage program that provides long-term costs and ensures a planned and preventative approach to maintenance. Being launched are: ESPecially for Your PT6 engine, which provides the first 400 hours of coverage for free to customers of new PT6A engine-powered aircraft; and an enhancement to P&WC’s current ESP plan offering, which enables customers to apply their ESP plan investment toward a new engine of the same model or a new engine conversion at time of overhaul.

“We continue to push ourselves to think outside of the box – about how we best serve our customers as well as deliver the greatest value and return on investment,” said Satheeshkumar Kumarasingam, Vice President of Commercial Services. “We’ve proven the bottom-line value of the ESP plan to thousands of customers as a unique solution that delivers a planned approach to OEM-backed engine maintenance. And we continue to innovate our maintenance coverage options with the launch of new and enhanced programs. Today’s announcement is a testament to the program’s ongoing evolution in delivering comprehensive pay-per-hour coverage.”

ESPecially for Your PT6 engine plan: First 400-hours of coverage at no cost

This past July, P&WC introduced the ESPecially for Your PT6 engine plan to aircraft OEMs as a way to support new aircraft sales and deliver optimal value to customers of new PT6A engine-powered aircraft. The plan includes P&WC’s world class ESP program with the first 400 hours of engine coverage at no cost to customers, representing a value of up to $50,000 per engine toward future maintenance. Additionally, after the first 400 hours of no-cost coverage customers will receive a reduced ESP plan rate until their first overhaul.

kodiak pt6a

“In three months since we launched ESPecially for Your PT6 engine plan, the enrollment in the program has been outstanding,” said Kumarasingam. “With the PT6A engine, we’re delivering innovative hardware and responsive care – . In fact, we’re seeing interest from aircraft OEMs to incorporate ESPecially for Your PT6 engine plan into their own maintenance packages to offer the most comprehensive ‘tip-to-tail’ aircraft coverage.”

New Engine ESP Plan Option: Apply your ESP investment toward a new engine or new engine conversion at Time of Overhaul

For customers already enrolled in an ESP plan and contributing on a per-flying-hour basis, P&WC has enhanced the plan to allow customers to select a new engine of the same model or a new engine conversion upgrade at time of overhaul for an additional cost.

“Exceptionally simple and flexible, this ESP plan enhancement is applicable on all active P&WC engine programs and gives our customers the ability to choose how their investment in ESP pay-per-hour plan coverage is applied at the time of overhaul,” continued Kumarasingam. “In addition to a higher residual value and/or a performance upgrade, customers will have all of the advantages that come with a new engine – from first run warranty and a parts service policy in full, to improved aircraft resale value.”

About the Eagle Service Plan

Simple to use yet comprehensive, P&WC’s ESP plan is an engine maintenance service plan for which operators pay a fixed monthly fee based on engine hours flown. For all ESP programs, plan members simply select the level of coverage that best fits their operation and pay an hourly rate based on the number of hours flown each month. All coverage levels include:

  • Engine overhaul/refurbishment
  • Hot Section Inspection/refurbishment
  • Basic unscheduled engine maintenance
  • Basic unscheduled accessories repair
  • Recommended product support improvements at engine shop visits
  • Rental engine support

Visit us at NBAA BACE, booth 3239. Interested operators customers are invited to stop by the P&WC booth to speak with a customer service representative.

About Pratt & Whitney Canada

Founded in 1928, and a global leader in aerospace, P&WC is shaping the future of aviation with dependable, high-technology engines. Based in Longueuil, Quebec (Canada), P&WC is a wholly owned subsidiary of United Technologies Corp. based in Farmington, Connecticut, provides high-technology systems and services to the global aerospace and building systems industries.

How PT6A-Series Engine Testing Works

How Is Your Engine’s Performance?

When asked by my company to submit an article, I thought it might be interesting to take a look at engine testing.  Many people are experienced in the operation, maintenance, repair, etc., of the PT6A engine, but engine testing seems to remain somewhat of a mystery! Let’s take a look at it!

Continue reading How PT6A-Series Engine Testing Works

The PT6 Remains True To Standards, Even In Changing Times

Air Tractor Front w COV LogoOne of the things that we truly appreciate at Covington Aircraft is the engineering innovations that go into aircraft designs. The PT6 engine is an ideal example of such a feat of design, since it has maintained its initial structure and mechanisms, but has also allowed for retrofitting older engines to perform with greater stability and efficiency. This has allowed for pilots to vastly extend their range of flight, and it has also allowed for flight in more diverse environmental conditions.

Continue reading The PT6 Remains True To Standards, Even In Changing Times