propeller care & maintenance for the amphibian presented by charles “skip” seila

Propeller Care & Maintenance Propeller Care & Maintenance for the Amphibianfor the Amphibian

Presented byPresented by

Charles “Skip” SeilaCharles “Skip” Seila

The propeller is probably the single The propeller is probably the single most neglected component on an most neglected component on an

aircraft.aircraft.

On takeoff, propeller tip speeds On takeoff, propeller tip speeds approach the speed of sound. The approach the speed of sound. The

blades must absorb not only the blades must absorb not only the punishing vibration of the engine’s power punishing vibration of the engine’s power pulses, but also vibration caused by the pulses, but also vibration caused by the oncoming airstream. Centrifugal loads – oncoming airstream. Centrifugal loads – those forces that try to pull the blade out those forces that try to pull the blade out of the hub – amount to of the hub – amount to 1010 to to 2020 tonstons per per

blade.blade.

The blades twist and flex. The stresses The blades twist and flex. The stresses imposed on the prop are more imposed on the prop are more

concentrated in the small areas that are concentrated in the small areas that are nicked or cut. These nicks and nicked or cut. These nicks and

scratches act as stress risers, which can scratches act as stress risers, which can weaken the blade enough to eventually weaken the blade enough to eventually

cause blade failure.cause blade failure.

TOPICSTOPICS

* Fixed Pitch Propellers.* Fixed Pitch Propellers. * Non-Feathering Constant Speed Propellers.* Non-Feathering Constant Speed Propellers. * Full-Feathering Constant Speed Propellers.* Full-Feathering Constant Speed Propellers. * Propeller Governors.* Propeller Governors. * Proper Care and Maintenance.* Proper Care and Maintenance. * Overhaul Periods.* Overhaul Periods. * Dynamic Balancing.* Dynamic Balancing.

Fixed Pitch PropellersFixed Pitch Propellers

Fixed Pitch PropellersFixed Pitch Propellers

* Pitch set for “Cruise” or “Climb”.* Pitch set for “Cruise” or “Climb”. * Can be set for other angles per the * Can be set for other angles per the

manufacturers allowable specifications. manufacturers allowable specifications.

* Pitch can only be reset at an approved propeller * Pitch can only be reset at an approved propeller shop.shop.

* Pitch is limited as to how many times it can be * Pitch is limited as to how many times it can be reset as it becomes “work hardened” at an reset as it becomes “work hardened” at an unknown given time.unknown given time.

Non-Feathering Constant Non-Feathering Constant Speed PropellersSpeed Propellers

McCauleyMcCauley

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers – McCauley Propellers – McCauley

* Takes oil pressure to change pitch.* Takes oil pressure to change pitch. * Lack of oil pressure or you have a fixed * Lack of oil pressure or you have a fixed

pitch propeller.pitch propeller. * Only lubricated at overhaul.* Only lubricated at overhaul.

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers – McCauley “Threadless”Propellers – McCauley “Threadless”

* Takes oil pressure to * Takes oil pressure to change pitch.change pitch.

* If it has a large snap * If it has a large snap ring at the base of the ring at the base of the blade as shown here – blade as shown here – it is a “threadless”. it is a “threadless”.

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers – McCauley “Threadless”Propellers – McCauley “Threadless”

* To inspect. Place the blade in the vertical * To inspect. Place the blade in the vertical position and with your thumb and forefinger on the position and with your thumb and forefinger on the tip, check for fore & aft movement.tip, check for fore & aft movement.

* Movement of 1/8 “ is acceptable.* Movement of 1/8 “ is acceptable. * If movement exceeds 1/8”, do * If movement exceeds 1/8”, do notnot remove the remove the

propeller. It is repaired right on the aircraft.propeller. It is repaired right on the aircraft. * Excessive movement is * Excessive movement is notnot critical to flight. It critical to flight. It

diminishes at the first rotation of the propeller and diminishes at the first rotation of the propeller and is purely psychological.is purely psychological.

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers – McCauley “Threadless”Propellers – McCauley “Threadless” * If it has a small allen screw in the middle of * If it has a small allen screw in the middle of

the hub, it probably is “oil filled”.the hub, it probably is “oil filled”. * The oil has a red dye in it to detect early * The oil has a red dye in it to detect early

cracking in the hub.cracking in the hub. * In order to prevent unwanted red dye * In order to prevent unwanted red dye

indications when no possibility of cracking indications when no possibility of cracking exists, it is highly recommended to exists, it is highly recommended to dynamically balance the aircraft. dynamically balance the aircraft.

Non-Feathering Constant Non-Feathering Constant Speed PropellersSpeed Propellers

HartzellHartzell

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers - HartzellPropellers - Hartzell

Takes oil pressure to Takes oil pressure to operate.operate.

Is lubricated every 100 Is lubricated every 100 hrs. /annual inspection.hrs. /annual inspection.

Non-Feathering Constant Speed Non-Feathering Constant Speed Propellers - HartzellPropellers - Hartzell

Note the 2 zerk fittings Note the 2 zerk fittings on each side. on each side.

They line up perfectly They line up perfectly with the bearings.with the bearings.

Remove the opposite Remove the opposite one when applying:one when applying:

- Aeroshell 5/6 on - Aeroshell 5/6 on

constant speeds.constant speeds.

- Aeroshell 6 on- Aeroshell 6 on

turbine propellers.turbine propellers.

Full-Feathering Constant Full-Feathering Constant Speed PropellersSpeed Propellers

HartzellHartzell

Full-Feathering Constant Speed Full-Feathering Constant Speed Propellers - HartzellPropellers - Hartzell

* Lubricated at 100 hr. * Lubricated at 100 hr. or annual inspection.or annual inspection.

* Attains pitch change * Attains pitch change on initial start from oil on initial start from oil pressure from the pressure from the governor.governor.

* Lack of oil pressure * Lack of oil pressure willwill result in feathering. result in feathering.

Full-Feathering Constant Speed Full-Feathering Constant Speed Propellers - HartzellPropellers - Hartzell

* This view shows the * This view shows the propeller in the feather propeller in the feather position. However, the position. However, the spring had to be cut for spring had to be cut for us to demonstrate the us to demonstrate the actions of this actions of this propeller. Seeing this propeller. Seeing this spring as it really is spring as it really is should remove any should remove any doubt that this doubt that this propeller propeller willwill feather! feather!

Propeller GovernorsPropeller Governors

Propeller GovernorsPropeller Governors

* Simply put – it is a * Simply put – it is a high pressure oil high pressure oil pump.pump.

* An inertia flywheel * An inertia flywheel maintains the setting maintains the setting that you made in the that you made in the cockpit.cockpit.

Proper Care and MaintenanceProper Care and Maintenance


* File the leading edges of the blades with a * File the leading edges of the blades with a fine file. No rasp or coarse file!fine file. No rasp or coarse file!

* File * File allall blades evenly. blades evenly. * Do * Do notnot use the shank of a screw driver for use the shank of a screw driver for

burrs. That only rolls the metal back in and burrs. That only rolls the metal back in and does nothing to prevent further damage.does nothing to prevent further damage.

* Keep in mind that to pass overhaul * Keep in mind that to pass overhaul requirements, blades are measured on requirements, blades are measured on width and thickness. Blades are expensive.width and thickness. Blades are expensive.


Burrs or nicks (stress risers) on leading or Burrs or nicks (stress risers) on leading or trailing edges must be repaired by using the trailing edges must be repaired by using the formula of 10X the depth of the damaged formula of 10X the depth of the damaged area to determine the necessary area area to determine the necessary area required to be repaired.required to be repaired.

Start with a file, then emery cloth and then Start with a file, then emery cloth and then crocus cloth to remove all file markscrocus cloth to remove all file marks

Do Do notnot wash your propeller. Wipe it clean wash your propeller. Wipe it clean and finish with a clean oily rag.and finish with a clean oily rag.

Propeller Care and MaintenancePropeller Care and Maintenance


* To “store” your propeller properly after flight:* To “store” your propeller properly after flight:– 2 bladers – horizontally.2 bladers – horizontally.– 3 bladers – 2 up and 1 straight down.3 bladers – 2 up and 1 straight down.– 4 bladers – 2 up and 2 down.4 bladers – 2 up and 2 down.

- Storage in this manner prevents rain or moisture from - Storage in this manner prevents rain or moisture from settling in the cavity at the base eliminating the settling in the cavity at the base eliminating the opportunity for moisture to seep in and case corrosion opportunity for moisture to seep in and case corrosion or destroy the affectivity of any lubrication.or destroy the affectivity of any lubrication.


* Stay away from water puddles. Why? Ever * Stay away from water puddles. Why? Ever notice the vortexing when running up over notice the vortexing when running up over water? The blades are so thin that one tip water? The blades are so thin that one tip may decide to go to one side while the other may decide to go to one side while the other blade tip takes to the other side and now the blade tip takes to the other side and now the prop is out of track. Avoid the vortex prop is out of track. Avoid the vortex scenario. This can be real costly.scenario. This can be real costly.

““___________” Overhaul Periods___________” Overhaul Periods

What’s missing ?What’s missing ?

The word “recommended”.The word “recommended”.

IT”S IT”S GONEGONE ! !

It’s history.It’s history.

It isn’t there anymore.It isn’t there anymore.

It doesn’t exist.It doesn’t exist.

Overhaul PeriodsOverhaul Periods * Hartzell Service Letter-----HC-SL-61-61Y* Hartzell Service Letter-----HC-SL-61-61Y “ “Propeller – Overhaul Periods and Service Propeller – Overhaul Periods and Service Life Limits for Hartzell Propellers, Life Limits for Hartzell Propellers, Governors, and Propeller Damper Governors, and Propeller Damper Assembllies”. Assembllies”. * McCauley Service Bulletin SB137Y----”Revised * McCauley Service Bulletin SB137Y----”Revised

time between overhaul (TBO) specifications”. time between overhaul (TBO) specifications”.

Overhaul PeriodsOverhaul Periods

* If you go past the TBO limits, you are * If you go past the TBO limits, you are

all alone with no back-up or support.all alone with no back-up or support.

* If anything happens, it’s at your own * If anything happens, it’s at your own

risk.risk.

* It’s a gamble and it is up to you to see* It’s a gamble and it is up to you to see

if it is worth it.if it is worth it.

Dynamic Dynamic

Propeller Propeller

BalancingBalancing

Dynamic Propeller BalancingDynamic Propeller Balancing

The Basics of VibrationThe Basics of Vibration– Definition Definition – Why it happensWhy it happens– How it is measuredHow it is measured– How we correct itHow we correct it


DefinitionDefinition For the purpose of Propeller Balance, For the purpose of Propeller Balance,

vibration can be described as: vibration can be described as: “the unwanted, unproductive, cyclic “the unwanted, unproductive, cyclic oscillation oscillation of the propeller and engine of the propeller and engine assembly about its assembly about its rotational axis.”rotational axis.”


Why Does It Happen?Why Does It Happen? When the weight of a rotating propeller and When the weight of a rotating propeller and

engine assembly is not equally distributed, the engine assembly is not equally distributed, the dominant or heavy point attempts to continue dominant or heavy point attempts to continue moving in a moving in a straightstraight line. The resulting force line. The resulting force attempts to pull the assembly outside its attempts to pull the assembly outside its rotational axis. The assembly then orbits what rotational axis. The assembly then orbits what would be the normal center of rotation, causing would be the normal center of rotation, causing vibration.vibration.


Understand that Understand that anyany imbalance at the imbalance at the center of rotation amplifies itself as it travels center of rotation amplifies itself as it travels out to the tip of the propeller. The tips being out to the tip of the propeller. The tips being thin vibrate augmenting the vibration and thin vibrate augmenting the vibration and also show a lose in efficiency.also show a lose in efficiency.


How We Correct ItHow We Correct It Improve manufacturing methodsImprove manufacturing methods Remove and replace Remove and replace Static BalanceStatic Balance Static Balance + Dynamic BalanceStatic Balance + Dynamic Balance


Vibration-Related Complaints Vibration-Related Complaints Passenger complaints of noise in the cabinPassenger complaints of noise in the cabin Cracked exhaust stacks and sheet metalCracked exhaust stacks and sheet metal Higher than normal occurrence of engine and prop Higher than normal occurrence of engine and prop

oil leaks and light bulb failuresoil leaks and light bulb failures Physical movement of airframe (buzz in the seat, Physical movement of airframe (buzz in the seat,

yoke, rudder pedals)yoke, rudder pedals) Malfunctioning or failed avionicsMalfunctioning or failed avionics

Dynamic Propeller Balancing Dynamic Propeller Balancing

How It Is MeasuredHow It Is Measured Sensor TypesSensor Types

– Displacement - Measures physical Displacement - Measures physical change of position.change of position.

– Velocity - Measures the rate of change of Velocity - Measures the rate of change of displacement with time.displacement with time.

– Acceleration - Measures the rate of change of Acceleration - Measures the rate of change of velocity with time.velocity with time.


Remember that dynamic balancing will Remember that dynamic balancing will prolong the life of the engine, propeller, prolong the life of the engine, propeller, airframe and avionics.airframe and avionics.

Before dynamic balancing and right after Before dynamic balancing and right after propeller installation, it is best to put a few propeller installation, it is best to put a few flight hours or good high end runs on it first. flight hours or good high end runs on it first. This will allow the blades to take their “set” This will allow the blades to take their “set” and eliminate the need to re-do the and eliminate the need to re-do the balancing later on.balancing later on.


Data Collection & ProcessingData Collection & Processing The vibration sensor is installed The vibration sensor is installed

on the engine as near the front on the engine as near the front bearing as possible. The bearing as possible. The Phototach is mounted on the Phototach is mounted on the cowling, behind the propeller. cowling, behind the propeller. The reflective tape is applied to The reflective tape is applied to the back side of the target the back side of the target propeller blade in line with the propeller blade in line with the Phototach beam. The mass is Phototach beam. The mass is located by the relative located by the relative occurrence of tach trigger and occurrence of tach trigger and mass passage at the radial mass passage at the radial sensor location.sensor location.


Data Collection & ProcessingData Collection & Processing As the heavy spot on the As the heavy spot on the

propeller passes the location of propeller passes the location of the vibration sensor, the sensor the vibration sensor, the sensor generates and sends an generates and sends an electrical pulse to the analyzer. electrical pulse to the analyzer. The Reflective tape triggers a The Reflective tape triggers a response as it passes the response as it passes the Phototach, which then sends an Phototach, which then sends an electrical signal to the analyzer. electrical signal to the analyzer.


Data Collection & ProcessingData Collection & Processing The process is The process is

repeated while the repeated while the analyzer averages out analyzer averages out errors caused by errors caused by momentary vibration momentary vibration events outside the events outside the running average.running average.


Data Collection & ProcessingData Collection & Processing A solution is then A solution is then

provided by the provided by the instrument based on a instrument based on a stored influence stored influence coefficient or a coefficient or a calculated test weight. calculated test weight. If required, the process If required, the process is then repeated for is then repeated for refinement of the refinement of the solution.solution.


The Balancing ProcessThe Balancing Process Where to place the weightsWhere to place the weights

– Test weights can be placed under the spinner Test weights can be placed under the spinner retention screws. It may be necessary to use retention screws. It may be necessary to use longer screws for the test weights. If doing so, longer screws for the test weights. If doing so, account for the delta between the normal and account for the delta between the normal and the longer screw. Be sure you are measuring the longer screw. Be sure you are measuring the angles in relation to the sensor or tape as the angles in relation to the sensor or tape as you specified in the setup being used.you specified in the setup being used.

Fundamentals of BalancingFundamentals of Balancing

Avoiding the PitfallsAvoiding the Pitfalls Adjust the speed of the prop as closely as Adjust the speed of the prop as closely as

possible to the exact target RPM on EVERY possible to the exact target RPM on EVERY run. A change in RPM will change the run. A change in RPM will change the influence of an attached weight. Subsequent influence of an attached weight. Subsequent solutions will not have the same calculated solutions will not have the same calculated results at different speeds.results at different speeds.


If an established influence for the engine If an established influence for the engine and prop combination being balanced is not and prop combination being balanced is not being used, the first weight the analyzer will being used, the first weight the analyzer will ask you to install is a TEST weight. This ask you to install is a TEST weight. This weight may cause the vibration amplitude to weight may cause the vibration amplitude to increase. The intention of the test weight is increase. The intention of the test weight is only to induce a measurable change, not only to induce a measurable change, not necessarily reduce the vibration.necessarily reduce the vibration.


There is no difference in the propeller There is no difference in the propeller balance procedure for a radial engine, balance procedure for a radial engine, opposed engine, turboprop, geared, variable opposed engine, turboprop, geared, variable pitch, or fixed pitch propeller.pitch, or fixed pitch propeller.


The Balancing ProcessThe Balancing ProcessPermanent weights may be installed under the flange or on the bulkhead. If installed under the flange, offset from spinner attaching screws by four times the diameter of the spinner screws.


Remember that when dynamic balancing Remember that when dynamic balancing you are balancing from the engine mounts you are balancing from the engine mounts forward.forward.

Dynamic balancing is Dynamic balancing is notnot a “cure all”, as it a “cure all”, as it can not compensate for gear doors that do can not compensate for gear doors that do not close properly, worn control surface rod not close properly, worn control surface rod ends, etc.ends, etc.

It is becoming the professional opinion that It is becoming the professional opinion that allall engines with propellers should be done. engines with propellers should be done.

Thanks so much for your time and Thanks so much for your time and we hope that in some way you have we hope that in some way you have

gained from this seminar.gained from this seminar.

propeller care & maintenance for the amphibian presented by charles “skip” seila

Documents

turbine propellers

fixed pitch propellers

constant speeds

speed of sound

pitch set

charles skip seila slide

propeller governors

propeller tip speeds