FREQUENTLY ASKED AIRCRAFT MAINTENANCE QUESTIONS
Why does my Cessna nose gear shimmy?
The bouncing between the steering bungee springs is this "shimmy." Any looseness in any part of the nose gear steering system will cause this problem. Resealing the shimmy dampner will not always solve the problem. The root of the problem is usually excessive looseness in the scissor links, excessive looseness in the steering collar, incorrect steering bungee adjustment, steering eye bolts installed at the incorrect dimension, under inflated nose strut, under inflated nose tire. All of these items are repairable by shims, bushings, bolts and dimension checks. Please call (888) 618-8133 for parts or to answer questions.
Why is my aircraft getting harder to start or impossible to start when it is hot?
First, gap the spark plugs. If the magneto is at all weak, see spark plug gaps on the main page for reference. Second, have the mags checked for proper contact point gap and inspection of distributor block and carbon brush. If any problems are found, have the parts replaced. For magneto parts see Aircraft Parts Quick Reference.
What type of lube do I use on the landing gear?
Can I use this same lube for wheel bearings? See airframe lube chart below for quick reference of lubes and greases by Aeroshell.
NOTE: The military specifications listed above are not mandatory, but are intended as guides in choosing satisfactory materials.
Products of most reputable manufacturers meet or exceed these specifications.
Why do I keep seeing this black material around rivets and sheet metal seams? See Photo
Be sure to read the instructions on any lube or corrosion proofing materials. This is becoming more common. In the application of these lubes and corrosion inhibitors, "more is not better." All aircraft engines and airframes vibrate. As long as the rivets and sheet metal parts are dry, this vibration does not seem to cause any problems or it hasn't for years. If excessive amounts of lube or corrosion inhibitors are used, it seeps into the lap seams and around rivets. The vibration and now the lubricant will cause the rivets to come loose causing this black smoke trail, also called "smoking rivets." Major repairs of skins and structures have been made due to this "more is better" idea. Read the instructions carefully. Some owner/operators that were told to treat their airframe at each annual are now trying methods of wiping out the inside of their wings and under the floor boards to remove any excess material.
My Cessna 150, 152, 172 seems to be low on power but the compression check is good?
The primary cause of low power is reduced to the carburetor airbox if the engine itself is in good working order. When you do your run-up and pull carb heat you get an RPM drop (reduction in power) this is due to hot air entering the carburetor. The most common problem seen is the seals on the sides of the flapper valve in the carb airbox get worn out and in some cases are missing. This allows hot air to enter the carburetor around the sides of the flapper valve all the time, even if the carb heat is off. This causes you to be losing a little bit of power all the time and not know it. The flapper valve can be repaired with a new seal to correct this problem.
Can I Use AN-Bolts for my Sensenich Prop?
It is always best to use the bolts the propeller manufacturer recommends. Although they may be more expensive, they go through a rigorous quality inspection process, random sampling, and routine surveillance of the manufacturer by Sensenich to ensure quality, conformity and safety. Sensenich "bolts are made to the same material and process specifications as an AN-bolt with the exception of the thread length. The primary concern is that a bolt does not bottom out in the engine flange bushing. This normally leads to bolt fatigue and possible failure. If you look at a standard AN bolt, there are very few threads. Maybe a half inch. There may be enough there for your installation but not someone else's. Most airframe installations are slightly different. Some use two bulkheads, some use one, some bulkheads are thicker than normal, etc. Another problem you may have is finding standard AN bolts that are long enough for the installation. You may be able to get an AN6H-43A but an AN6H-83A is not so readily available." In many cases, a prop may be removed for inspection and reinstalled with the same hardware, thinking that the hardware must be correct. This is not the case. The wrong bolts could have been installed many years ago. Remember, most of the General Aviation fleet is 30+ years old. Always inspect the bolts for damage and proper length. Call us at (888) 618-8133 to order your specific Sensenich Propeller bolts.
When Should Brake Linings Be Replaced?
When Should Teflon Tape Be Used?
NEVER use teflon tape on aircraft fittings. Many instrument failures are caused by loose teflon tape getting into the instrument air system. Teflon tape will melt when exposed to Avgas. Do not use teflon tape on fuel drain valves. The proper sealant should be used on drain valves, instrument fittings and fuel line fittings. See the Airframe Supplies page to choose the correct sealant.
Do you hold a pilot certificate? Find out what types of preventative maintenance you can perform on any aircraft you own or operate.
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