Propeller Maintenance In The Fall
by Maurice Wills,
Canadian Propeller Ltd.
“With winter just around the corner, a lot of aircraft are getting ready for winter storage. Let’s take a look at what we can do as far as your propeller is concerned.”
Check your Prop Logbooks:
For: Calendar Maintenance Requirements
Traditionally, many propellers calendar out in the spring and need servicing. Now, with the Transport regulation changes, many propellers are on a 10 year calendar life. If your propeller needs servicing before spring we advise that you send it in over the winter, perhaps even before doing your own aircraft storage. Look at your prop log in the fall and if required, send it to a shop to be serviced over the winter and it will be ready to install in the spring.
This allows you and your prop shop time to work together to rectify any potential problems and if necessary, locate required parts which could possibly save you money. Then you can be up and running for your spring fishing trip.
For: Time X’d by Hours
For example, if your propeller has 30 hours left on it till TBO at fall time and you fly 400 hours a summer, but don’t fly it in the winter, it may be good planning to send it into the prop shop early. With this option, you should have no down time in the summer. This also allows for possible long lead times from the manufacturers for parts or to prevent other snags.
For: AD’s Against Propeller
Not all propellers in Canada are on a 10 year calendar cycle. If there is an AD against the propeller which specifies a shorter calendar time this takes precedence. For example, AD 81-13-06R2 on Hamilton Standard Hydromatic Propellers calls for a maximum of 5 years calendar between inspections. Another is AD 97-18-02R1 on Hartzell steel hub propellers with double shoulder blades, models HC82VK, A2VK etc., which also calls for a maximum of 5 calendar years between inspections.
For: Manufacturers Recommendations
Manufacturers recommend a calendar life of 5 to 6 years because this is what they estimate the seal life to be. If your calendar is getting up over this time you should be having a closer look for oil and grease leaks.
Propeller Winter Storage:
The three areas you want to look at are the 1) blades, 2) hub assembly, and 3) spinner and bulkhead.
Give the blades a good visual inspection. Check the leading edges for any nicks and gouges. Dress if required. Alodine and paint for corrosion protection. Run your hands over the leading and trailing edges because sometimes you can feel a crack where you might not have seen it.
Here you want to check for loose blades. To check, place one blade in the horizontal position, (making sure the mags and master switch are off), then shake the tip of the blade leading edge to trailing edge. On a McCauley propeller you are allowed up to 1/8” of play at the tip. On Hartzell Compact props you should have no play. Centrifugal force pulls the blades out when they are rotating and tightens up the propeller. A good guide that you can use is to compare between blades. For example, on a three blade propeller if all blades are consistent it is probably normal wear. If two blades are tight, and only one is loose, it may need to be serviced.
On constant speed propellers you twist the blades from course to fine. To do this gently twist the blades to check for looseness. Normally all blades will have a little rotational play. If any blade moves excessively (generally 1° is the maximum allowed) you could have a worn link or damaged pitch change component.
For blade shake and blade twist, the main thing to look for is consistency between the blades.
Hartzell steel hubs (propellers with blade clamps) also have a blade tape across the blade and clamp. Check the tape and see if they line up. This checks to see if the blade has moved in the clamp. If the blade moves you will get a blade angle split which will cause vibration. We have seen props in the last two years that have had this happen.
THE SPINNER & BULKHEAD:
Remove the spinner and check for cracks in the shell and bulkhead. We have had three cracked bulkheads on the new McCauley C203 installation on the Cessna 180. One customer was complaining of an intermittent vibration and two were found on annual inspection.
THE HUB ASSEMBLY:
Here you want to look for oil leaks, grease leaks and cracks.
There are two types of Hartzell propellers, steel hubs and compact hubs.
The steel hub is composed of an external blade clamping system on a hub. Look for grease leaks, oil leaks and cracks. Check to see if the plating is rusted, and grease as per manufacturers specifications.
The compact hub has a two part hub, which clamps around the blades. Look for grease leaking from the blade roots and cracks in the hub. Grease as per manufacturers recommendations.
McCauley hubs are either grease filled or oil filled. There is no greasing required. Look over the hub for grease or oil leaks. Some propellers have red dyed oil installed. If you see any red oil do not fly, and contact your local shop. This dye can indicate a cracked hub or blades.
Counterweight propellers such as 2D30 and 3D40 need to be greased. There are two grease nipples in the hub. Aeroshell no. 5 grease is recommended. Also, behind the counterweight caps there are two slots that the cylinder rides back and forth in. Grease here and also check for looseness in the cylinder.
For propellers installed on crop sprayers or Norsemen, we recommend that they get a shop visit every two years. The high cycles and the 3D40 hubs installed on these aircraft really wear prematurely. This can prevent down time in your busy season.
Aircraft in Canada are operated in harsh conditions and your airplane propeller takes the brunt of it. However, with periodic maintenance and good storage techniques, your propeller will be ready for the spring fishing trip, the crops can be sprayed and the Norseman, Otter and Beaver will be back in the air.
I have touched on some of the winter and preventative issues for a prop to get the longest service life possible.
A really good idea is to visit your local shop. Take a tour. Educate yourself. There are some great websites to expand on the propeller maintenance issues that we have brought forward. Hartzell also has a very good CD on Propeller Maintenance that you can order through a Hartzell Factory Approved Repair Station at no charge. Remember, when it comes to propellers, Pro-active is better than Re-active! The ideas presented here are guidelines. Please be sure to check your owner’s manual for more details and manufacturers recommendations.
Related Propeller Maintenance Websites:
Maurice Wills is General Manager for Canadian Propeller Ltd.
Canadian Propeller is Western Canada’s Hartzell Propeller Approved Repair Station and a McCauley Propeller Factory Authorized Service Station. Maurice has been in the propeller industry and an AME for over 25 years. He has been President of Canadian Propeller for 14 years.
For more information, contact Maurice at 1-800-773-6853, or www.canadianpropeller.com