Category Archives: aircraft engine maintenance

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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Tracking Starts And Flights: Understanding Abbreviated Cycles and Full Cycles for PT6 Engine Maintenance

As most of you know, there are life-limited components in a PT6. These components include the CT and PT Disks and the Compressor Disks. After a certain number of cycles they must be replaced.

starts and flights pt6a compressor disk

Continue reading Tracking Starts And Flights: Understanding Abbreviated Cycles and Full Cycles for PT6 Engine Maintenance

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Protecting One of Your Largest Investments In Your Aircraft? Maintaining the PT6A

While this article is primarily all about what you do with your LARGE PT6 engine during the off season, the very first paragraph or two will cover a couple of other “Nice to Know” topics.  Large in this article relates to PT6A-60AG, -65AG, -67AG, -67F and any other model with a -60 series engine installed, like a -67R, -65B, -67D etc.   If there’s a 6 as the first number of your engine model…this article is for YOU.

Continue reading Protecting One of Your Largest Investments In Your Aircraft? Maintaining the PT6A

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4 Quick Fall Engine Tips: Now’s the Time for Preventative Maintenance on your PT6A

The squirrels in our front yard are gathering pecans, acorns, hackberrys, canned peanuts, potatoes, oranges, etc. You think I’m safe in predicting a rough winter? They’re getting ready. I would like to offer some tips for helping you get ready.

10.9.2020PT6A

Continue reading 4 Quick Fall Engine Tips: Now’s the Time for Preventative Maintenance on your PT6A

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The Perils of Having an Oil Starved PT6A & What To Do About It

Sometimes things happen!  It’s not very profound, but it is very true.  Engines suffer through prop strikes, wire strikes, hot starts and hard landings.  Frequently, post incident inspections reveal minor damage and the engines are repaired and returned to service promptly.  Recently, engines have been brought to Covington for investigation because “things” have happened to them.  One was a reported incident of a starter/generator arcing.  The starter/generator malfunctioned and was replaced.  While the maintenance appears to have been performed properly, “things” still happen.  Here is what we found upon disassembly:

oil starved PT6a

An indication of electrical discharge was noted from the starter gear and all through the accessory gearbox. The #1 bearing failed, which in turn allowed the compressor to shift causing a severe rub of the compressor components and the compressor turbine blades. Another engine suffered from oil starvation:

Another engine suffered from oil starvation:

PT6A oil starved

And a third engine had a failure in the turbine area:

pt6a oil starved 2

Even though the engines pictured here suffered from in-flight shutdowns, all of the aircraft were able to land safely and all pilots walked away.

Although we understand that “things” happen, we don’t want them to happen to you.  If they do, we will work with you no matter where your previous maintenance was done, to ensure that you have a rental/replacement engine as quickly as possible to keep you flying.  Remember to be aware of changes in your engine or events that could cause damage.  Pay attention to the way it sounds (blade rubbing), looks (metal or debris in oil), smells (oil burning) and feels (vibrations) along with watching the gages.  You may be able to detect a problem before some ”thing” happens to your engine.

Need to have a certified expert look at your PT6A engine? Founded in 1972, Covington Aircraft is a world-leading aircraft engine maintenance, repair and overhaul facility specializing in the PT6A turbine engine and R-985 and R-1340 radial engines. We are a Pratt & Whitney Canada certified Distributor and Designated Overhaul Facility (DDOF), and provide world-class corporate and agricultural aircraft service.

Request maintenance by visiting here >>>> http://www.covingtonaircraft.com/contact-us/request-maintenance 

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Oil Analysis Technology Update-header

3 Key Benefits of Oil Analysis Technology

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

Recently added to the ESP™ plan, our (Pratt & Whitney Canada’s) Oil Analysis Technology is a powerful diagnostic and prognostic tool that helps customers avoid unscheduled events. We outline some key benefits below.

1. A SIMPLE, USER-FRIENDLY SAMPLING PROCEDURE

Taking routine oil samples from your engine and sending them for analysis is a fast, simple process that gives detailed insights into engine health that wouldn’t otherwise be possible.

This technology enables operators like Germany’s Arcus Air, an airline that offers chartered cargo and corporate flights, to plan maintenance in advance, thereby minimizing the risk of unscheduled events and maximizing engine availability.

Pratt & Whitney’s Oil Analysis Technology is a powerful tool that helps us better understand the health of our engines. We receive clear and concise data that allow for a quick overview but also for deep insights. Daniel Bürcky, Chief of Maintenance, Arcus Air

The sampling procedure is designed to be as user-friendly as possible. We provide customers with a kit that contains everything they need, from a syringe and tube or O-rings for collecting the oil to a pre-paid envelope with all the necessary paperwork for sending the sample to the lab in Canada.

Customers simply need to collect a sample during scheduled engine maintenance, then have the package picked up by FedEx. In return, they’ll receive a report outlining the results, along with recommended follow-up actions.

The sampling interval is typically from 200 to 300 hours, meaning that for a typical business jet or general aviation operator, samples only need to be taken once or twice a year, notes Frédérique Richard, Senior Manager, Oil Analysis Technology.

2. EXPERT INSIGHTS THAT ENHANCE OPERATIONAL CONFIDENCE

Oil analysis technology is used to monitor trace particles in oil-wetted components such as carbon seals, gears and bearings. It compares their current condition with the signature of other healthy engines in the fleet. Once a component deteriorates past a certain threshold, our team will provide specific maintenance recommendations.

It’s like going to the doctor to have a blood sample taken, explains Frédérique. If the doctor analyzes your blood and sees that you have a health issue, like slightly high cholesterol, she’ll suggest doing something like changing your diet or exercising more. Our Oil Analysis Technology works in a similar way.

We look at the data and if anything needs to be done, we help customers figure out the right next steps. We give them a tailored ‘prescription’ – a specific maintenance recommendation to address the matter before it becomes an issue. Frédérique Richard, Senior Manager, Oil Analysis Technology

The insights gained from this technology therefore give customers greater operational confidence by letting them know when they should keep a closer eye on specific components or take action to repair or replace them.

One example is carbon seals. If these components are left to deteriorate, it could eventually lead to unplanned maintenance events, which may entail unexpected costs like hangar rental, spare engine shipment or cancelled revenue flights.

All of that could be avoided with our Oil Analysis Technology.

“In some cases, we can tell hundreds of flight hours in advance if a carbon seal is deteriorating,” says Frédérique. “Once we see that, we’ll issue a recommendation to monitor its condition more frequently. When action is required, we’ll advise the operator to proactively remove the engine at the next scheduled maintenance and send it to the shop for replacement.”

Thanks to this technology, we’ve been able to identify early deterioration patterns and recommend proactive maintenance on a number of engines. These customers were able to schedule maintenance and avoid the disruption of situations such as cabin air contamination and metal in oil. Frédérique Richard, Senior Manager, Oil Analysis Technology

3. A CONTINUOUSLY EVOLVING TECHNOLOGY

To date, with the help of customers around the world who want to go beyond basic engine maintenance and are embracing early detection, we have collected tens of thousands of oil samples.

The more data there is to work with, the more detailed and accurate our Oil Analysis Technology becomes, because it’s not static. It continues to evolve, as the new data helps us to refine engine oil signatures and fine-tune our algorithms.

“It’s an ongoing journey,” says Frédérique. “We keep investing in the technology and working to improve it.”

The advanced analytics that we use allow us to go deeper than human analysis alone could accomplish. This enables us to identify engines at risk of a particular issue, prioritize maintenance work, and ultimately drive operational improvements, cost savings and greater engine availability Frédérique Richard, Senior Manager, Oil Analysis

technology combined with other technologies such as our FAST™ solution, it enables customers to understand their engine inside out and fly with peace of mind. If our Oil Analysis Technology is like a blood test, FAST is like an MRI. These prognostic and diagnostic tools complement each other, contributing to a more holistic view of engine health.

Oil Analysis Technology is one of several recent additions to our ESP™ maintenance program. Learn more here.

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Essentials For Your PT6A Engine Oil Analysis

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

In an aircraft engine, oil is much more than just a lubricant. It plays a number of other important roles, including cooling, cleaning and noise reduction. It’s therefore vital to monitor and analyze oil to ensure it’s doing its job properly.

WHEN AND WHAT TO ANALYZE

Engine oil sampling and analysis are recommended if a visual inspection reveals that the oil is very dark, has an unusual odor or exhibits other abnormal properties. You don’t necessarily have to change the oil, but at the very least, it should be analyzed to determine its total acid number (TAN) and water content.

Typically, the water concentration in brand-new oil varies between 0.02% and 0.04%, or 200 and 400 parts per million (ppm). However, water can enter the engine’s oil system due either to accidental contamination during compressor wash or normal condensation. Since aircraft engine oils easily absorb water and moisture from the air, their water content will rise over time. If it exceeds 1000 ppm, the TAN may rise as well, eventually leading to engine component corrosion.

HOW TO SAMPLE AIRCRAFT ENGINE OIL

When you take an oil sample, identify it with the brand name, engine serial number, total run time (oil life) and engine time since new (TSN) or time since overhaul (TSO). Have the sample analyzed for its TAN and water content by an approved laboratory. If necessary, ask the lab to analyze the oil viscosity and additives as well.

If a parameter exceeds the established limit, it’s recommended that you: 1) drain and discard the oil from the tank; 2) check the condition of the oil filter and, if needed, replace it with a new one; 3) refill the tank with fresh oil.

If you have access to the right kits, you could also perform the analysis yourself. Use a Titra-Lube TAN Test Kit to analyze the oil’s TAN and a HydroScout Analyzer kit for the water content.

Read more: Oil Analysis Technology Makes Proactive Maintenance Easier.

RACK YOUR OIL CONSUMPTION

Every time you add oil into your engine, write down the amount so that you can calculate the average consumption. Check this figure against the limits indicated in the maintenance manual. If the engine is using more oil than it should, there may be a part that needs maintenance. For example, a damaged O-ring could be causing a leak, or something may be happening in the engine that’s burning up extra oil.

Oil is key to your engine’s health and performance, so give it the attention it deserves by following the advice above.

Read all technical tips and talk from our experts about aircraft engine oil on Airtime.

A BRIEF HISTORY OF AVIATION GAS TURBINE ENGINE LUBRICANTS

The earliest aviation piston engines were lubricated with natural oils such as castor oil and refined mineral oils. However, they lacked the thermal-oxidative stability needed for high-temperature mechanical systems and would form deposits like gum and lacquer on metal surfaces.

In the 1950s, following research efforts aimed at improving thermal-oxidative stability, synthetic polyester-based lubricants became the base stock of choice for aviation gas turbine engine oils. Thanks to their chemical properties, these lubricants are effective over a wide temperature range, from -65oF to 425oF. They possess good thermal-oxidative stability, high lubricating film strength, good surface wetting, and low friction and wear rates, making them ideal for aircraft engines.

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A Quicker Way to Overhaul Your PT6-A Engine

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

Aircraft engine overhauls are all about flying like new and they require careful planning. It all takes time and a maintenance scheduling. Imagine replacing your engine with one that has already been overhauled, all at a guaranteed price?

Continue reading A Quicker Way to Overhaul Your PT6-A Engine

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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.

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

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