As one of the safest and most popular forms of transportation, flying remains an important form of travel in the United States.
In 2011, there were an estimated 224, 475 total active aviation craft in the United States. In 2015, there were 24,142,000 general aviation flight hours logged. Flying remains an important part of the economy as well. Worldwide commercial helicopter sales were expected to reach nearly $5 billion in 2017. Additionally, approximately 131,500 aircraft mechanics and service technicians were employed in the U.S. in 2017 and the Federal Aviation Administration supports more than 10.6 million jobs in the U.S. each year.
One of the most important parts of routine maintenance for helicopters is rotor maintenance. It’s not unusual for a helicopter rotor to need repairs. By its very nature, the job of a helicopter is to get close to the action and because of that a helicopter rotor can take a beating. Whether a helicopter rotor strikes a tree, strikes a wire, strikes a hangar or undergoes any other kind of damage, repairing it is a major part of helicopter maintenance.
Some of the most common types of damage to a helicopter rotor are:
- Ground handling
Corrosion is a natural tendency for metals to return to their original oxides and salts. As it relates to a helicopter rotor, corrosion can begin on the surface and progress inward where it can eventually lead to a helicopter blade being destroyed. The speed of corrosion on metal depends on several factors including:
- Operating Environment
- The Alloys Used in Manufacturing
- Paint and Primer Systems Used
- Preventative Maintenance Measures Used to Slow Corrosion
When it comes to preventing corrosion, the alloys used in manufacturing a helicopter rotor and the paints and primers used are a starting point for defense against corrosion. When the metal on the rotor is exposed, that’s when maintenance is required. Washing a helicopter rotor with water and soap, followed by application of a corrosion-prevention compound is a good way to keep it clean and ward off corrosion.
Erosion of a helicopter rotor occurs when dirt, sand, ash and water particles come in contact with a rotor blade. Ash is one of the leading causes of damage to blades and rain isn’t far behind. To protect against erosion, blades can be protected with epoxy paint or erosion strips made of metal tape.
In addition to preventing corrosion, proper rotor track balance is important in general aircraft maintenance. Flying aircraft, especially helicopters can be fun, but rotor systems can develop unexplained vibrations. When that happens, chances are good there’s a good possibility that one of the blades has shifted.
There are two types of vibration that affect a helicopter rotor: vertical and lateral. Vertical vibration happens when rotor blades don’t provide equal lift and lateral vibration happens when there is unbalanced mass distribution of the rotor system or there is misalignment. To fix the problem, helicopter manufacturers can provide rotor track and balancing testing and can also offer dynamic propeller balance, vibration analysis, fan balance testing and other services.