Valuable Technical Information for Aircraft Propeller Owners

The following links represent often requested technical information; however, feel free to contact us to discuss any technical questions.

When ordering a fixed pitch propeller, it is important to know the difference between a tapered crank shaft and a flanged crank shaft.  Be sure to alert your sales person as to which you may have.  The bolt kit for each is different and not interchangeable.  A tapered shaft may require bushings in the back of the propeller. 

A tapered crank shaft is pictured top right and a flanged crank shaft is picture bottom right.

Tapered Crank Shaft or Flanged Crank Shaft?


Sensenich Wood Aircraft Propeller Model Designations

W C 58 S K L 62 G

W - Wood Propeller

    C - Composite fabric must be applied

        58 - Basic propeller diameter in inches

             S - Blade design

                 K - Hub Drilling

                     L - Propeller rotation if left hand (if right hand, no designation)

                         62 - Geometric pitch in inches

                              G - Denotes options: G: glass fabric covering U: synthetic leading edge

Sensenich Aluminum Aircraft Propeller Model Designations

74 D M 6 S6 0 56

74 – Basic propeller diameter in inches

     D – Blade design

         M - Hub Drilling

             6 - Mounting bolt diameter in 1/16 th's of an inch

                 S6 - Spacer Length in 1/4's of an inch

                      0 - Diameter reduction in inches

                          56 - Geometric pitch in inches

Sensenich Composite Aircraft Propeller Model Designations

3 B 0 R5 R 68 C 0

3 - Number of blades

    B - Shank design and sizing

        0 - Hub configuration

            R5 - Hub drilling and mounting bolt size

                 R - Blade rotation

                     68 - Basic propeller diameter in inches

                          C - Blade design

                              0 - Propeller diameter reduction in inches


(Typical) Hartzell Aircraft Propeller Model Designations

HC-B 3 T N-3 DY

HC - Hartzell Controllable

     B - Basic Design Characteristic

         3 - Number of blades

             T - Blade Shank

                 N - Mounting Flange

                     3 - Specific Design Features

                         DY - Identifies minor modifications


McCauley Aircraft Propeller Model Designations

McCauley Constant Speed propeller model numbers have two important constants - one at the beginning that designates the number of blades and one at the end that specifically identifies the propeller model.

 A numerical value at the beginning of the model number in either the first or second position (i.e. B2 or 2A) indicates the number of blades. (This first constant will be followed by a two digit number value between 31 and 37 which reflects a particular McCauley design.)

 The most important designator in a McCauley Constant Speed Propeller Model will be the two or three digits following the "C" at the end of the model number. If there is only two digits following the “C" the propeller will be a threaded propeller and an obsolete design.  If there are three digits following the "C" the propeller will be a threadless blade design and is current production.  A Propeller Technician may refer to a McCauley Propeller as a C66 (threaded) or a C203 (threadless) - names which in "propeller speak" accurately identifies a McCauley Constant Speed Propeller Model.

The C200 series - two-bladed constant speed threadless non-feathering propellers

The C300 series - two-bladed constant speed feathering propellers

The C400 series - three-bladed constant speed non-feathering propellers

The C500 series - three-bladed constant speed feathering propellers

The C600 series - Garrett Turbine Engine propellers  - either three or four bladed

The C700 series - Pratt Whitney Turbine Engine Propellers - either three or four bladed

The C1000 series - Pratt and Whitney Turbine Engine Propellers - five bladed

The C1100 series - Garrett engine propellers - five bladed

 In addition to the Propeller Model number there is a blade model number for all McCauley Propellers.  The propeller diameter is a result of the difference between the first two digits and the dash number at the end of the blade model number. For example in the blade model 90DA-2 the propeller will have an 88 inch diameter (90 inches minus 2 equals 88 inches). The "DA" indicates the blade design.

Choosing between a fixed pitch wood or a fixed pitch metal airplane propeller

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

  • 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.

 Most newer airplane designs require metal aircraft propellers:

  • Metal propellers are more efficient because of a thinner airfoil design.
  • A certified prop shop can change the pitch of a metal propeller.  (This change in pitch must of course comply to the 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. 

Type Certificates 

A type certificate is awarded by aviation regulating bodies to aerospace manufacturers after it has been established that the particular design of a civil aircraft, engine, or propeller has fulfilled the regulating bodies' current prevailing airworthiness requirements for the safe conduct of flights under all normally conceivable conditions (military types are usually exempted). Aircraft produced under a type certified design are issued a Standard Airworthiness Certificate.

If the manufacturer or some other organization or person wants to make a major change to the design or use of the product, approval from FAA must be obtained. In these cases, the FAA issues a “supplemental” or “amended” type certificate.  To look up a specific Type Certificate for your aircraft, they are available at the FAA website at the address below:  Hold down the control key to access all links:

What Federal Regulation governs my aircraft?  Part 91?  Part 135?

 FAR -- Federal Aviation Regulation--federal laws and statutes govern all US aviation operations.

Part 91 -- the section of the FAR's that govern the operation of any general aviation flight.  Many corporate flight departments and all non-professional pilots function under these rules. Ninety-five percent of aircraft in the United States function under Part 91. 

Part 121 -- the section of FAR that governs major airline operations.

Part 135 - the section of FAR that governs any charter flight.  These "rules" are actually federal laws and they specify in great detail the requirements for equipment in the airplane, the training minimums and operational limits for the pilots, flight attendants, and maintenance personnel.

PART 61, 141, 142 -  the section of FAR covering pilot certification and flight school operations: the pilot certification and standard flight school (Part 61), the integrated curriculum type school (Part 141) requiring slightly fewer flying hours, and a new Part 142 program allowing replacement of more flight time with advanced flight simulators.

To determine the type of Governor needed, you will need to answer the following questions before calling your propeller technician:

  1. What is your aircraft make and model?
  2. What is your engine make and model?
  3. What is your  propeller make and model?
  4. If synchronizing is required be sure to mention this to your salesperson.
  5. Has another governor been used for this application?  If so, which model?