When the engine is not on the airplane…
We have discussed many topics regarding how to care for your airplane's engine while it is operating. Several recent instances have made me think we should also discuss engine handling when the engine is removed from the aircraft.
If your engine must be removed and shipped for repair or overhaul, you must ensure that you follow the guidelines in the engine maintenance manual. Mishandling engines and power sections has caused several issues, leading to very costly repairs.
When you read the engine chapter in your maintenance manual (72-00-00) under the servicing topic, the bulk is how to remove, install, store, and ship the engine or one of its modules. Types of containers, necessary tooling, temperatures and humidity, and details and instructions are offered. The very first thing is a word of caution. “To prevent possible bearing damage…” is how caution starts. Then it warns users to use shock-mounted skids for ALL engine transportation. If you have noticed, rubber isolators are on the skid base for the engine or the approved power section boxes. These isolators are there to absorb the vibration caused by traveling. In most states I have been to, some roads highlight the need for these isolators. You know the streets I’m talking about.
We see engines in all kinds of conditions. People hit things; engines ingest things; many times, engines make it to TBO and are sent for an overhaul. What is heartbreaking is when the engines are not appropriately secured for shipping. It is sad to see the damage and additional costs caused by mishandling.
What happens when an engine is damaged due to mishandling? The most common is the damage sustained due to an engine being dropped. As the operator/owner, you must supply details to help us establish how much inspection needs to be done. We need to know the circumstances that brought us to this point, the type of surface the engine or container struck, and the height from which it struck. This helps to determine the severity of the damage we are looking for. If an unapproved shipping skid has been utilized, we rely on Pratt & Whitney Canada engineering to aid us in determining a course forward. In most events, the engine must be disassembled to some extent to inspect the mainline bearings. Depending on the model, the engine has six or seven of these. Some work scopes have dictated the replacement of all the mainline bearings. At several thousand dollars each, multiplied by six or seven, you can see how that can add up quickly.
Inspection will also include looking for engine mount damage and checking the condition of external tubing, lines, brackets and other sheet metal parts for distortion, dents, and bending. Then we open the engine to check for internal damage to gears, disks, blades, etc. Even a bench check of the accessories is done. If damage is done to the accessory, it is submitted for overhaul. It can be a very extensive inspection added to whatever repair the engine required that caused the initial removal.
In all cases, the manual calls out a rubber-mounted steel cradle to hold and support the engine during transit and storage. I encourage everyone to review your engine maintenance manual regarding shipping and storage. Talk to your maintenance provider if you need help finding an appropriate shipping skid. I know that we have sent shipping containers worldwide for our customers. Be sure to check with your insurance carrier and discuss coverage of your engine when it is not on the airplane. Not many folks give much thought to engine handling when the engine is off the aircraft. I hope each of you does and doesn’t end up costing yourselves even more.
Robert Craymer has worked on PT6A engines and PT6A-powered aircraft for the past three decades, including the last 25+ years at Covington Aircraft. As a licensed A&P mechanic, Robert has held every job in an engine overhaul shop and has been an instructor of PT6A Maintenance and Familiarization courses for pilots and mechanics. Robert has been elected to the NAAA board as the Allied-Propulsion Board Member. Robert can be reached at robertc@covingtonaircraft.com or 662-910-9899. Visit us at covingtonaircraft.com.
