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propeller inspection

Replacing vs. Repairing Your Airplane Propeller

An airplane’s propeller is one of the most highly-stressed and most-overlooked components on any aircraft. During routine operation, 10 to 25 tons of centrifugal force is pulling the hub’s propeller blades. Also, the propeller blades are bending and flexing due to thrust and torque. 

Engineers design propellers to be properly maintained and to perform normally under these loads. But when damage occurs due to corrosion, stone nicks, or worse, additional unintended stress is imposed. In that case, the margin of safety may not be adequate. Operating an aircraft needing a propeller replacement or propeller overhaul can be a dangerous risk. 

Propellers may need a professional propeller shop’s special attention and capabilities for many reasons, such as scheduled overhaul limits, operating inspections, and major repairs. Not to mention – propeller replacements!

If you’re worried about your propellers or require a propeller governor repair or propeller overhaul, talk to the experts at Stockton Propeller. With decades of experience and free service area pick-up and delivery, we’re the propeller experts who keep you flying!

A Quick Recap On Composite Airplane Propellers

Airplane propellers have been around, well, since the first powered flight. In the early days of aviation, propellers broke at an alarming rate. This breaking was a function of being carved from wood, a porous and fibrous structural tissue.

Today aluminum and structural composite blades are standard, and repairing them when they get dinged has become commonplace. Damage can result from stones and other objects and impact with external objects or the ground.

Repairing a structural composite blade is quite different because instead of just removing material, composite repairs replace material lost to gouges and other damage.

Beyond their obvious weight advantage over aluminum blades, structural composite blades have additional benefits:

  • A longer service life
  • The ability to maintain an optimum airfoil shape over the propeller’s service life
  • An almost infinite fatigue life
  • An expert can repair most damage
  • Far more robust when it comes to erosion and impact
  • Can withstand a lot more impact without affecting its airworthiness
  • Can be repeatedly restored to factory-new shape and aerodynamics

While the composite materials that form propellers are incredibly durable, they are not entirely immune to operational damage. Propeller manufacturers have created and published protocols to help airplane operators and maintainers determine when and how to repair composite blades.

Overview Of Propeller Issues

Most airplane propeller issues fall into one of two categories: corrosion or physical damage.

Corrosion

One of the most insidious causes of damage to a propeller is corrosion, both external and internal. External corrosion is visible on the blades. Internal corrosion eats at the components within the variable-pitch propeller. Regardless of whether it’s internal or external, corrosion reduces the propeller’s structural integrity, as well as its performance.

Physical Damage

Physical propeller damage include nicks, dings, gouges, and cracks on both the propeller blades and the propeller governor. 

A propeller repair shop has the tools to do much more detailed inspections of propellers for cracks, including optical, eddy current, dye penetrant, and magnetic particle inspections. However, routine examinations for damage visible to the naked eye are crucial for good propeller health.

According to the FAA’s Advisory Circular AC 20-37E, “Limited minor repairs may be made on propellers by appropriately rated maintenance technicians either on the aircraft or upon removal of the propeller. Minor dents, cuts, scars, scratches, and nicks may be removed, providing their removal does not weaken the blade, substantially change weight or balance, or otherwise impair its performance.”

Why Repairing Is (Sometimes) Better Than Replacing

There are many valid reasons for repairing rather than replacing. These include: 

  • saving money, 
  • continuing working with a component that is otherwise known to be good, 
  • supporting good mechanics in their business, 
  • and saving the planet from a little more “airplane junk” in the dump.

Aircraft owners should consider all the costs of time, expense, and safety when considering what course to follow while performing maintenance

Some mechanics prefer replacement over repairing a component. All FAA-licensed mechanics are authorized to do most repairs or replacement tasks, as long as they have the proper training, tools, and documentation.

In truth, most of your aircraft’s components can be repaired by your trusted mechanic, as long as they have the proper training and tools. The question is, should you have the propeller repaired or replaced altogether?

It’s important to consider:

  • How critical are the components to my safety and the safety of future flights? (Hint: Propellers are VERY important!)
  • What are the costs of repairing versus replacing (including your own time, shipping costs, and parts/labor)?
  • How will propellor governor repair versus replacement affect the future reliability (and future maintenance cost) of your aircraft?

All manufacturers publish “time before overhaul” (TBO) guidelines for their propellers. These TBO guidelines are based on both the in-flight hours and the calendar months the propeller has been in service. These guidelines typically range from 1,000 to 3,000 flight hours and five to seven years in service. 

The Case For Replacement

So we’ve already covered the main questions on whether to deal with repairing vs. replacing above. 

Why else might someone choose to replace a propeller?

  • You’ve reached your propeller’s operational life limit.
  • It seems obvious, but it’s imperative to pay attention to your aircraft propeller’s time before overhaul (TBO). Flying your aircraft with propellers beyond their intended service life is inadvisable and potentially dangerous. Overhauling or upgrading your propeller is an investment in your aircraft’s future safety and performance. 
  • You are ready for a dramatic performance increase.
  • With new propellers, pilots can (potentially) improve aircraft performance with: 
    • shorter take-off distances, 
    • lower noise levels, 
    • better ground clearance, 
    • reduced tip erosion, 
    • increased climb rates, 
    • increased cruise speeds, 
    • and overall smoother operation. 

How Do You Know Which “Flight Path” To Take?

Okay, we’re sorry about that awful pun. 

But we’re not sorry about being the best in propeller governor repair or propeller overhauls. 

Talk to us. We’re the experts at Stockton Propeller. With decades of experience and free service area pick-up and delivery, we’re the composite propeller experts who keep you flying!

Categories
flight Uncategorized

Why is Aircraft Propeller Static Balancing Important?

One of the most enjoyable things to love about air flight is the sensation of being free of the ground and gliding smoothly through the air. The last thing you want to be thinking about when flying your airplane is an aircraft propeller overhaul. Your focus should be on the experience of flight and those enjoying it with you.

Unwanted vibrations can ruin the feeling of freedom and make flying less pleasant for both the pilot and any passengers. Vibrations can result in discomfort as well as the loss of revenue in the case of commercial pilots hoping for repeat passengers. Unwanted vibrations can result in passengers feeling unsafe and taking actions such as leaving negative reviews or taking their business elsewhere.Biplane sitting on runway in the sunset

Vibrations from the aircraft propeller can also have an impact on cargo in the plane as it is shaken and shifts during flight. Vibrations could cause fragile cargo to break, or essential parts of the aircraft damaged over time. Improperly balanced aircraft propellers can drive up maintenance costs.

Aircraft propeller static balancing after the initial point of manufacturing the plane is typically done during aircraft propeller overhaul. Stockton Propeller is a full-service maintenance facility that can help you with your propeller overhaul or any other needed maintenance.

What is Aircraft Propeller Static Balancing?

Image of a propeller with a red planeAircraft propeller static balancing at a basic level ensures that the propeller is moving evenly through the air as it rotates. When conducting the balance, each propeller blade is weighed to make sure that it weighs the same as all of the others. Each part of the propeller weighing the same ensures that gravity will affect each part of the propeller evenly as it rotates through the air.

An uneven weight distribution during rotation will cause the propeller to vibrate. Even if the pilot or passengers of the plane cannot feel the vibrations themselves, the vibrations can have an impact on the engine. Pilots may accept vibrations as merely a part of the way in which the airplane’s engine works.

Pilots should consider having a static propeller balancing conducted prior to feeling any vibration. Pilots may not be able to notice any vibration or notice any changes that develop over time. Performing a static propeller balancing can avoid future maintenance issues.

How is an Aircraft Propeller Static Balance Done?

When professionals at a place like Stockton Propeller conduct a static propeller balance during an aircraft propeller overhaul, they remove the propeller from the aircraft. Then the propeller is mounted on a device called a mandrel, which allows the propeller to spin freely.

A properly balanced propeller should be able to move quickly. According to Bellwood Rewinds Limited, if turned slightly after a static balance is done, an object should stay in that location. This process is done the same way very much as tire balancing on a vehicle.

In an improperly balanced propeller, the weighty spot will be pulled by gravity downward. This allows the maintenance facility to discover unbalanced areas and fix them. Weights are added or subtracted from the area of the propeller hub nearest to the misbalanced propeller blade, which corrects the imbalance.

After the Propeller Static Balance is Completed

Once a propeller is evenly balanced, the maintenance staff will conduct what is known as a “blade track.” Each of the propeller’s blades path through the air is tracked and monitored. Workers mark where the blade tip passes an object, such as a track pointer or a spot on the wall. A properly tracking propeller should have each blade passing at the same location. Even a difference of 1/16th of an inch is too far.chrome covered plane propeller

If a propeller blade is out of track, then the “angle of attack” will be slightly different from the others when flying. This different angle can cause vibrations due to it moving through the air in a different path. A propeller that is out of alignment can mean that it was damaged, an issue which should be investigated further.

The Difference Between Static and Dynamic Propeller Balancing

Aside from static propeller balancing, which should always be performed, there is another common type of propeller balancing– dynamic propeller balancing. Although not absolutely necessary, dynamic balancing “fine tunes” the balance. 

Even small imbalances that are not noticeable to the pilot can cause damage to components such as instruments, radios, cowling and baffles and reduces the efficiency of the propulsion system. Unlike static propeller balancing, dynamic propeller balancing is conducted while the engine and propeller are in motion.

Sensors are attached to the engine and propeller and run through the full range of RPMs. As this is done, the sensors are analyzed for possible vibrations. The technology can recognize and determine how much weight needs to be added or subtracted.

In a dynamic propeller balancing the technician should have proper training and the equipment must be in good working order and clean.Errors or inaccurate data can result from this. These errors can lead to the weight being added or taken away from the wrong location on the propeller and increase the potential for damage.

In static propeller balancing, the evidence of a proper balance can be seen in the movement of the propeller and that when rotated, it will remain in place. Doing both can produce high-quality results. Pilots should be sure to conduct research before they decide on a maintenance facility to best suit their needs.Twin propeller plane sits on runway

Where to Turn for Aircraft Propeller Static Balancing?

When you are looking for a maintenance facility to perform your aircraft propeller overhaul, it is important to select a company with the experience and expertise to conduct all of your needs. Stockton Propeller is a full-service propeller overhaul and maintenance facility with the needed equipment and expertise to perform your propeller balance.

Whether it is done as a part of an aircraft propeller overhaul or because you feel an unwanted or unusual vibration, an aircraft propeller static balance is an important piece of your maintenance plan.

Categories
business flight

The Basic Aerodynamics of Flight

For those learning about the principles of aerodynamics, this article seeks to cover some of the basics. Like how does a propeller work on a plane, and what are the four forces of flight.

Aircraft are complex machines. Each part must work together not only to propel it forward but also to overcome gravity for it to fly. The four forces of flight include thrust, weight, lift, and drag.

If you are concerned that there is an issue with your propeller and want to have a propeller overhaul to optimize the aerodynamics, contact Stockton Propeller. Stockton Propeller is a full-service propeller overhaul and maintenance facility with the needed equipment and expertise to perform your needed maintenance and repairs.

Thrust

One crucial component of an airplane’s aerodynamics is the force of thrust. The propulsive force created by the propeller or rotor works to counteract the effects of two of the other four forces of flight — weight and drag.

Airplane wing and tail flying though a cloudy sky

Your airplane’s propeller generates thrust by utilizing the principle of Newton’s Third Law. Newton’s Third Law states that for every action, there will be an equal and opposite reaction. A propeller or jet engine pushing air to the rear will have the effect of moving the plane forward unless some other force halts it. 

The plane’s propeller will push enough air past it to cause the aircraft to move in the opposite direction of this force. The propeller must work with a high level of efficiency to provide the necessary thrust for takeoff and flight.

The amount of thrust needed will change throughout the flight. As explained below, the weight of the plane’s propeller is just one component of weight to overcome.

You must also accommodate the mass of the fuel needed to power the propeller flight. As the flight continues, fuel is consumed.  As the fuel is consumed, its mass is reduced.  As mass is reduced, less thrust is needed. 

Weight

Another of the four forces of flight is weight. Weight is the force caused by gravity.

This weight includes not only the aircraft itself, but also the mass of the cargo, fuel, pilot, and any passengers. Increased weight means that the aerodynamic forces of thrust and lift must also increase.Diagram of airflow over the wings of an airplane

In propeller flight, the weight of the propeller itself must be accounted for in the mass calculations. Also, weigh or estimate the weight of all cargo, fuel, passengers, and anything else loaded onto the aircraft.

If this weight is not accurately determined, it will affect the plane’s performance.  It will also result in miscalculating the fuel volume needed for the flight, and even the plane’s ability to take off safely.

If the plane cannot generate enough lift and thrust to compensate for the weight, then some weight must be removed. To reduce the excess load, replace materials with stable, yet lighter materials, or carry fewer passengers and less cargo.

Drag

Drag is a rear-facing force caused by the disruption of airflow over the wing, fuselage and other components of the plane. The force of drag must be overcome through the forward momentum of the aircraft. To reduce drag, you may also need to alter the design of the aircraft.

Think about the comparative wind resistance of something like a paper airplane vs. a cup held concave side toward the airflow. The pointed shape of the paper airplane allows the air to flow smoothly over its surface and wings. Paper airplane flying due to aerodynamic principles

On the other hand, the cup will catch the air and not allow it to flow past. Catching or trapping the airflow will result in much more drag. The plane’s shape will allow the air to continue in the direction it was initially flowing without much interruption.

When questioning how does a propeller work on a plane, consider the concept of drag resulting from all aspects of the aircraft. Examine the surface of the plane, as well as the position and shape of the propeller. Optimize the propeller blades to create the least amount of drag possible while creating enough power to propel the plane. 

Lift 

According to NASA, lift “is the force that directly opposes the weight of an airplane and holds the airplane in the air.” Every component of the airplane works together to counteract the effect of gravity on the plane. 

Even with an efficient propeller, a plane in propeller flight would not fly if the rest of the aircraft was not designed to generate lift. 

Lift is a complex and often misunderstood principle. Lift is the force produced by the changes in air pressure above and below the aircraft components, most specifically the wings. 

For lift to take place, a fluid or gas: in this case, the air around the plane is required. In addition to a fluid or gas, you also need a solid to deflect the flow — the airplane wings, flaps, ailerons, among others. The fluid or gas must also be in motion.Diagram of flow of air over a plane flying landscape

In order to understand how does a propeller work on a plane, you need to put the fluid in motion by propelling the aircraft through it.  Planes cannot take off without being powered to generate this initial forward momentum.

The curved shape of the wing creates lift by making the air move faster across the top of the wing and lowering the air pressure.  This reduced pressure results in less force pushing down on the wing while maintaining an upward force under the wing, creating lift.

How Does a Propeller Work on a Plane to Optimize the Forces of Flight?

The propeller, coupled with the engine, is what produces enough thrust to move a plane forward. Once the plane is moving forward, the remaining four forces of flight combine to provide the necessary lift to get the aircraft in the air.

These aerodynamic forces of flight, all working optimally together, result in an efficient and safe voyage.

If your propeller is not operating as efficiently as needed to optimize thrust, contact Stockton Propeller. Stockton Propeller is a full-service propeller overhaul and maintenance facility that can assess your plane and perform any necessary maintenance.

 

Categories
business

What License Do you Need to Fly a Twin Blade Propeller Plane?

There are many questions to be answered when a pilot first begins to look at the training and certification process. Among those are the questions like where to take classes, what sort of license is needed for the pilot’s goals, and what sort of equipment they want to fly. For example, what kind of license would you need to fly a twin-blade propeller plane?

It may seem overwhelming to try to wade through all of the information available and all of the different options to pursue to become a certified pilot. Aspiring pilots need to learn the variety of available licenses and make the best judgment of what will best suit them while considering factors such as:

  • Investment of time
  • Cost of training
  • Availability of training in their area
  • Personal goals they wish to accomplish
  • Type of plane they would use or purchase

Aside from the initial cost of purchasing a plane, pilots should also bear in mind the relative costs of maintaining that airplane. Stockton Propeller, a full-service propeller overhaul and maintenance facility serving Northern California, can help you with your propeller repair, no matter what kind of plane you end up flying.

Types of Certifications

One of the first questions a trainee pilot must answer is what type of certifications are available for them to pursue? All beginning pilots begin their path to licensure as “Student Pilots.”After achieving this status and meeting other requirements, it is up to them to decide what they would like to pursue after this step. They may choose:

  • Private Pilot Certificate
  • Recreational Pilot Certificate
  • Sport Pilot Certificate

The distinction between these certifications may seem confusing at first, but pilots need to consider a few fundamental differences. Pilots should also bear in mind that if they achieve one level of certification, they can always continue on and gain additional certification if they want additional flexibility of the type of craft they want to fly, how high they would like to fly, or if they would like payment for their flying.

Pilot entering the cabin of a private plane with another pilot and the cockpit in the background

Private

This certification is the most popular of the three options. While it does involve additional hours of training as it takes 40 hours to achieve, it offers the greatest level of flexibility in what a pilot can do after gaining their license. This license may give students the greatest return on the investment of their time and money into training. The Private Pilot License will allow pilots to pursue further training that can lead to becoming a commercial pilot or even a flight instructor.

After finishing training, this license will allow pilots to pursue additional training to receive their Instrument and Commercial Pilot certifications. A multi-engine certification will let pilots fly twin-propeller planes that require special training in what to do if one of the engines breaks down.  The Commercial accreditation will also allow pilots to be paid for their flying, giving compensation for their time and expense of training.

Father and son in the cockpit of a small plane flying

Recreational

The Recreational Pilot License is considered a step down from the Private Pilot License. There are more restrictions placed on the pilot, in particular, no flying professionally.

A Recreational License prohibits pilots from flying aircraft with more than 180 horsepower.

This certification may appeal to some due to the lower level of required time in flight training at 30 hours. Less time required also requires a lower monetary investment.

One restriction placed on this license is that the pilot may only fly lower than 2000 feet AGL (above ground level) and that the aircraft flown by the pilot is not certified for more than four occupants.

The restrictions placed on this license may not be an issue for many pilots that choose this option. However, a pilot may later decide to continue their training and earn greater freedoms given by a Private Pilot certification.

Pilot with headphones sitting in an open air cockpit of small plane

Sport

What if you only want to fly smaller lighter craft? In 2004 the Sport License was created by the FAA in response to the growing trend of flying these innovative crafts. Pilots with this certification have greater restrictions on what sort of aircraft they can fly.

Pilots who want to fly planes with only themselves and perhaps one passenger on board should look into this license.

These planes are considered easier to fly, and the certification takes less training and less expenditure to achieve. Only 20 hours of flight training are required. This may appeal to pilots whose only goal is flying this sort of craft, as some of the additional training requirements do not apply.

Additionally, pilots who work toward this certification do not need to have a medical certificate as they would with other licenses. These lesser requirements may make this appealing to some flyers.

If pilots pursue this certification but then decide they would like to fly a greater variety of aircraft, they may continue their studies to earn one of the other certifications.

When To Seek Qualified Help and Repairs For Your Twin Blade Propeller Plane

As they continue the process of deciding which license to pursue, pilots need to consider many factors. One of those is what expenses they will incur when it comes to purchasing or renting a plane, as well as what associated costs are likely to be met with when repairs are needed.

It is important for pilots to thoughtfully consider where to have each aspect of their planes maintained and repaired. Because their very lives depend on the results of this maintenance, the choice of maintenance facility is a vital one.

Stockton Propeller is a full-service propeller overhaul and maintenance facility providing service to individuals, FBOs, and air carriers. So, no matter what type of pilot certification you have, we can assist with your governor and propeller repair and maintenance needs.