PROP TIPS

TIPS ON PROPELLER CARE AND SAFETY

TIPS ON THE CARE OF A WOOD PROPELLER

TIPS ON CARE OF A HARD WORKING PROPELLER

FAQ's

TIPS ON PROPELLER CARE AND SAFETY

Tip # 1 Tachometers: Have the tachometer checked annually. Mechanical tachometers are notoriously inaccurate and subject to drift over their lifetime. If your engine and propeller combination has one or more yellow arcs or red restricted arcs within the normal operating range – common to a lot of four-cylinder Lycomings – then it is vital that the tach accurately guides you out of these trouble spots. These limitations are in place because of vibration characteristics of the engine and propeller combination and can lead to long term trouble if routinely ignored.

Tip #2 Checking Blade Track: Blade track is the ability of one blade to follow the other in the same plane of rotation. Track is held to reasonable limits to prevent roughness. To check track, place a smooth board just under the tip of the lower blade. On controllable props, move the tip fore and aft carefully through its small range of motion, making small pencil marks at each position. Center the blade between these marks and draw a line the full width of the blade. Repeat this procedure with another blade tip. The lines should be separated by not more than 1/16 inch. Differences greater than 1/16 inch may be an indication of bent blades, improper installation or foreign particles between the hub and crankshaft mounting faces.

Tip #3 – The Run-up of Constant Speed propellers: For constant-speed propellers during run-up keep an eye on the oil pressure and temperature. Pressure should be in the normal, green arc range, and the temperature should be rising according to outside conditions. Because the constant-speed propeller needs both good oil pressure to do its job and oil thin enough to be pumped through the smaller passages of the prop, tit is important to keep these parameters in mind, particularly for cold weather departures. A takeoff with cold oil will result in a poorly governed prop and a possible over speed event. In subfreezing conditions, it could take 15 to 30 minutes to get minimum oil temperature. Storing the airplane overnight in a heated hangar or calling for preheat will help greatly.

Tip #4 – The installation of Your Propeller: A propeller must be installed by an A&P mechanic. Generally the proper installation bolt torque is shown on the blade decal near the hub. Always have the blade track checked after the hub bolts are tightened. (Blade track is the ability of one blade to follow the other in the same plane of rotation.) Every propeller is accurately balanced at the factory. If the propeller-engine combination feels rough in flight, ask your mechanic to remove the propeller, rotate it 180 degrees on the engine crankshaft flange, and re-install. Again check blade track. This provides a means to verify that the crankshaft flange is true.

Tip #5 – Towing your airplane: Do not use the propeller as a tow bar to move your aircraft. Either use a tow bar on your planes’ steerable nose wheel or use the areas of the airframe designated by the manufacturer as safe for push /pull pressure. Pulling or pushing with the propeller could severely damage components inside the hub.

Tip #6 – Avoid run up in areas containing loose stones and debris: Propellers can sustain significant damage when operating over loose stones and debris. If the airplane is parked on a gravel surface, move it to a hard surface before starting the engine. When taxiing to a tie down spot on gravel, shut the engine down on hard ground and use a tow bar to move the airplane into the tie down spot.

Tip #7 – Prior to flight, take a few precautions to ensure that your propeller will perform as needed: Listen and feel for unusual noises and vibration. Look for loose bolts or a tip that might have separated during the start and taxi sequences. All props vibrate to some extent during operation. However, propeller roughness may be caused by 1) bent blades 2) blades out of track due to improper mounting of the propeller on the engine shaft, 3) imbalance, 4) a propeller loosely mounted on engine shaft, 5) angles between blades are out of tolerance 6) spinner imbalance due to improper mounting or dirt, snow or ice inside the shell.

TIPS ON PROPELLER CARE AND SAFETY

TIPS ON THE CARE OF A WOOD PROPELLER

TIPS ON CARE OF A HARD WORKING PROPELLER

FAQ's

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TIPS ON THE CARE OF A WOOD PROPELLER

TIPS ON PROPELLER CARE AND SAFETY

TIPS ON THE CARE OF A WOOD PROPELLER

TIPS ON CARE OF A HARD WORKING PROPELLER

FAQ's

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TIPS ON CARE OF A HARD WORKING PROPELLER

Gayle’s Father owned and operated an FBO and was a crop duster. When asked to write about maintenance of the AG propeller or any hardworking propeller we collaborated to write the following informative article:

As the daughter of a Crop Duster, I enjoyed listening to my Dad’s stories around the dinner table but never thought a lot about what it took to maintain my Dad’s airplane propeller. Not until I decided to earn my living in the Aviation Industry. I now work with my husband in the aircraft propeller industry.

When asked how to prolong the life of a propeller on the average AG plane, my first thoughts were, “Don’t take off on gravel roads. Don’t hit power lines. Keep the prop in the box it came in!” Seriously, as the reader already knows, maintaining a propeller on an Ag Plane is much more challenging than that of the average aircraft.

In addition to the regular challenges that face all plane owners such as corrosion, nicks, and prop strikes, the Ag Pilot has the wear and tear resulting from taking off and landing on gravel, dirt and unpaved airstrips along with the added corrosion threat from the pesticides and chemicals he uses. Additionally, the aerobatic like turns and maneuvers shorten the life of the AG propeller, a fact reflected in the manufacturer’s mandated shorter-than-average recommend time between overhauls (TBOs) established for Ag propellers.

If I owned and operated an AG Plane (Who knows?) here are the 8 best life prolonging, money saving strategies for that hard working propeller.

  1. Use restraint in removing nicks. If you are an Ag Pilot, you most likely act as your own mechanic. As the mechanic, use restraint in removing nicks and sharp edges from your own propeller. We frequently see propellers that have been filed below minimums in the field. In an overhaul, the Professional Propeller Technician (PPT) is trained to remove just enough to smooth all of the dings and blemishes. Even a PPT can cause a blade to go below minimum thicknesses to where a blade will be scrapped. Leave as much blade diameter, thickness and width as possible for the PPT to utilize during overhaul. We want your propeller to make overhaul!
  2. Wash your propeller daily. While it is a good idea for every owner to wipe down a propeller after use, it is absolutely critical for the Ag plane owner to remove the caustic chemicals that build up with each use.
  3. Send your prop to a Certified Repair Facility for a Midlife Inspection. Keep in mind that even though your propeller appears to be functioning, internal corrosion, especially in humid climates, could be destroying your propeller. Catch corrosion early!
    While conducting a Midlife Inspection, have your propeller resealed. During a reseal the propeller is taken completely apart, a visual corrosion inspection is conducted and all the seals are replaced. Usually the propeller is repainted and balanced at this time as well. This relatively inexpensive procedure (half the cost of an overhaul) can add life to your propeller through the early discovery of corrosion and other problems that can destroy your propeller.
  4. Paint your propeller. Paint helps protect your propeller. A Dress and Paint by a professional will add life to your propeller! This procedure can be done more frequently, but the mid life inspection is a convenient time to get your propeller painted.
  5. Never attempt to straighten a propeller blade yourself. Straightening your own propeller blade is illegal for a good reason. Compromised metal is very dangerous. Let the experts straighten your blade and determine if the propeller is safe to put back on your aircraft. When it comes to propeller maintenance, never were the words, "Better safe than sorry" more true.
  6. Look at your Manufacturer’s guidelines before attempting to grease your own propeller. Over greasing your propeller can potentially cause an out of balance condition. Review your manufacturer’s general guidelines on how to grease your propeller.
  7. Check propeller tracking frequently. If your propeller has been bumped or compromised, check the tracking. A change in tracking can be unnoticeable or cause severe vibrations. Improper tracking will cause the propeller to feel out of balance but the cure is distinct from balancing. While the mechanic can check the propeller tracking, once discovering your propeller is out of track, a PPT must realign it for you.
  8. Keep your propeller balanced, both Statically and Dynamically. A Static Balance is routinely performed on every propeller by a Certified Propeller Repair Station (CPRS) during an overhaul, mid life inspection or even during a simple Dress and Paint.
    A Dynamic Balance is performed on a plane with the engine running. Because CPRSs (or other Maintenance Facilities) charge additional fees for this service and because it is not “required”, the owner often chooses not to have this service performed. Penny wise but pound foolish! A Dynamic Balance will help mate the prop and the crank shaft together; save the bearings in a crank shaft; and enable the entire engine to run more smoothly.
  9. Be on the alert for oil or red dye. If you spot oil or red dye, try to locate the origin of the leak. The propeller is not always the source of the leak. Engine oil leaks caused from mounting the O ring or crank shaft seal are often blamed on the propeller. If red dye is evident, the propeller must be removed from service and sent for repair. Depending on the model of the prop and per the manufacturer’s instructions, you are allowed to see if the propeller will seal itself. As long as you are not faced with a severe leak of red dye, you may fly a couple hours "to get where you are going".

Hardworking, watch-the-bottom-line AG Pilots are often reluctant to bring their propeller in for professional inspections. The down time and expenses are delayed because the ever present fear is, “What if they scrap or red-tag my propeller?” The best strategy is to take care of your propeller and when you notice irregularities, have a professional look at your propeller immediately. A properly maintained propeller will have the longest life and save you money in the long run.

Lastly, manage the work your repair station performs on your propeller. Ask for a full inspection report before they begin work that includes price quotes on both labor and parts. You have a right to examine any scrapped parts and you are entitled to a full explanation of why those parts scrapped. Get price quotes from more than one repair shop and be sure to use a reputable Certified Propeller Repair Station.

TIPS ON PROPELLER CARE AND SAFETY

TIPS ON THE CARE OF A WOOD PROPELLER

TIPS ON CARE OF A HARD WORKING PROPELLER

FAQ's

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FAQ’s

  1. I had a prop strike is my propeller repairable?
    If the damage on your propeller tips allows you to reduce the diameter (the total length of the propeller) by less than the manufacturer’s prescribed minimum diameter, your propeller is often repairable. Some props do not allow for any reduction in diameter, others will allow up to 2 inches.
    If the leading edge, trailing edge, surface or tip of the propeller is damaged and in repairing the propeller the technician has to reduce any one of the dimensions below minimum dimensions allowed by the manufacturer, the propeller is not serviceable.
    If the blades are beyond repair, the hub is generally not reusable. Sometimes the internal parts of the hub can be reused after appropriate inspection. The manufacturer’s manual will outline any exceptions.
    Call us and we will help you make an informed decision regarding the serviceability of your propeller.
  2. When might I need to change my propeller?
    You MUST change or overhaul your propeller if you have a damaged or unserviceable propeller due to a strike or corrosion. Unseen internal corrosion destroys many propellers. The only way to properly inspect the surfaces of the hub and the blades for corrosion is through a teardown. You should overhaul your propellers if your propeller has reached recommended overhaul intervals based on either calendar time or flight hours. The manufacturer’s recommended TBO (flight time or calendar time) is mandatory for commercial aircraft.

Other reasons for changing your propeller include:
  1. If; you change your flying habits (ie used to fly from grass strip to cross country)
  2. Move from sea level to a high elevation city.
  3. To improve take off and climb.
  4. To make your plane quieter.
  5. To gain ground clearance.
  6. Propeller is damaged or unserviceable due to a strike or corrosion.
  7. If you are changing from wheels to floats or skis or visa versa.

Whatever the reason, changing your propeller demands careful consideration. We will help you investigate your options for upgrading to a higher performance propeller or in replacing your aging propeller.

  • If both a metal and wooden propeller are available for my aircraft and engine, which is a better choice?

  • While most newer designed aircraft require metal propellers, not all do! The new Diamond aircraft utilizes a wooden propeller! When both are applicable to your aircraft, consider all of the following before making your decision:
    • Wood props are lighter and result in an increase in payload.
    • Wood propellers cause less vibration. While metal props accumulate invisible flaws from vibrations and flexing, wood props are not affected.
    • In the event of a prop strike, the wooden propeller will itself be destroyed but in most cases not damage the crankshaft. After a metal prop strike, the engine should be disassembled and inspected.
    • Wood props must be sent back to the factory for overhaul.
    • Wood props are generally the less expensive choice.
    • Metal propellers are more efficient because of a thinner airfoil design.
    • A certified prop shop can change the pitch of a metal propeller. (This pitch change of course must comply with manufacturer’s specifications!)
    • Metal propellers can be overhauled at any FAA certified propeller facility.
    • Metal propellers retain their value better than wood as a trade-in for resale.
  • Should I use hours or time in service to determine if my propeller is due for an overhaul or replacement?
    All propellers have recommended overhaul intervals based on calendar time and flight hours. Depending upon the prop model, the amount of time in service could be 1,500 or 2,000 flight hours. It is important that calendar time be carefully considered at about 5 years in service. Too many pilots ignore the calendar limit!
    Consider the aircraft that flies fewer than 100 hours per year. At 100 hours per year, a typical propeller might not get checked for 20 years! This is clearly a bad idea! Your propeller should be overhauled at either the time or calendar limit, whichever occurs first! If the engine comes up for overhaul before the prop reaches either limit, most shops will recommend removing the prop and governor and having them overhauled at the same time!
  • How do I ship my propeller?
    If a propeller must be shipped (for trade in or repair) never apply tape directly to the blades. Wrap each propeller blade with 3 or 4 layers of corrugated cardboard applying additional layers to the tips.
    If your propeller is a variable pitch, wrap the hub with several layers of cardboard and then cover the hub with a box padded so as to keep the hub from direct contact during shipping.
    If you are using a wooden box for shipment use caution to insure that the propeller fits snugly and is well padded inside the wooden container as the propeller will sustain damage if room for movement exists inside the crate.
  • Is a Propeller Logbook important?
    Maintenance of your propeller logbook is very important. The logbook stays with a propeller and should be updated with each overhaul or refurbishment. When traded or exchanged, a logbook should accurately indicate the TSN (time since new) or TSO (time since overhaul).
    Accurate logbook entries will enhance the trade in value of your propeller. Without proper documentation, the propeller cannot be exported and it might be difficult to sell.
  • Can I paint my propeller myself?

    • While some try to paint their propellers themselves, I highly recommend that your propeller be repainted by a professional. Propeller repair stations will “dress and paint” your propeller using a high quality paint recommended for propellers.


  • Should I buy a wooden propeller or a metal propeller?

    • While wood propellers are not certified for many planes, for those for which they are certified there are some advantages:

    Most newer airplane designs require metal propellers: