Our engine mounts are a simplified solution to control the motion of an engine. Made up of few parts, they are quick and easy to install. While there is no standard expected life for engine mounts in service, it is vital to understand how to maintain and inspect them in order to maintain optimal conditions.
There are many factors involved in determining engine mount wear and how often they need to be replaced. These include where the aircraft is stored, storage temperature and environment, how often the aircraft is flown and flying behaviors.
We recommend conducting regular visual and dimensional inspections using guidelines from Parker LORD Products for General Aviation brochure to ensure your mounts are performing adequately.
Once installed, preventative care of your engine mounts is vital to maximizing their service life.
When inspecting mounts, start by examining the elastomeric material—look for loss of bond at adhesion points between the elastomer and metal components. This should be followed by checking for mechanical damage to the elastomer such as cuts or gouges. Finally, you should inspect for signs of environmental damage, i.e., gummy texture or swollen mounts that appear very hard or soft. To inspect mounts for elastomer to metal separation or loss of bond, a shim feeler gauge is inserted at locations where the rubber meets or is bonded to the rubber. The distance that it can be inserted is then measured. If the distance is greater than three millimeters, we recommend replacing the mounts. Note: Do not force the feeler gage into areas where separation has not occurred, this process should be conducted gently in order to preserve the elastomer and elastomer to metal bond.
If mounts have a shimmed sandwich mount, meaning they have an additional metal component within the elastomer section, appearing as an extra step or layer on the mount, this area should also be inspected. The feeler gauge is used to identify areas where there could be a loss of bond, so it can be used to check the bond at the shim location as well. This process should be continued with all the elastomeric components to ensure there are no areas where this inserted distance is greater than three millimeters.
A metallic visual inspection of the metal parts on the engine mount should also be conducted to locate signs of mechanical damage like cracks, deformed plates, scratches, nicks and gouges. Any of these can cause performance and installation variations. Damage to the attachments must also be considered. Are there loose bolts or missing lock wire?
Lastly, a dimensional inspection should be conducted to uncover any engine mounts in need of replacement. This includes checking the thickness of the elastomer section as well as the eccentricity, for each of the sandwich mounting halves. These values can be found in our GA engine mount inspection brochure.
Preventative care of engine mounts can have a significant effect on their service life. As elastomeric components, they must be kept clean and shielded from heat and fluid exposure. It is important to cover your mounts while cleaning the engine because those fluids can have harsh effects on the elastomer, thus influencing the life of the mounts. You will want to inspect them often to ensure they haven't been impacted. Your engine mount kit should also be changed with every engine overhaul. We recommend replacing all kit components at the same time because they each uniquely affect the performance of the mounts as a whole and should all age at the same rate. Because mounting kits have a specific orientation, mounts should not be flipped or rotated as that can cause performance limitations and installation issues.
Stay tuned for our next blog to learn more about the technology and design behind our engine mounts, plus what makes an optimized or “perfect” engine mount.
To learn more about our engine mounts and zero-maintenance shimmy dampers, check out our webinar or give us a call at 1-877-ASK-LORD.