Helicopter Vibration Analysis: Why It’s Necessary And How It’s Done

When you are operating an aircraft, it needs to be in optimal condition so that you and any passengers are safe. Regular maintenance for aircraft is essential, and helicopter vibration analysis is a key component in ensuring that you stay safe while in the air. Untangle the mystery of vibration in aircraft by finding out why monitoring it is important and how exactly you can do that.

Why Is Helicopter Vibration Analysis Needed?

While helicopter design has vastly improved over recent years, the current levels of vibration average between .05g and .1g. These levels are significantly higher than those in a jet-engine aircraft, which are typically below .01g. Although a helicopter’s vibration levels can never be fully eliminated, it is important to lower them as much as possible. The vibration negatively affects rotor blade structural integrity, firewalls, component life, instrumentation, and the operator’s comfort and control of the aircraft. Malfunctions in the aircraft, such as loose hardware, worn bearings, and unequally distributed mass in rotor blades, are common causes of an unusual amount of vibrations. As there is typically a large amount of vibration in a helicopter because of its regularly moving parts, parsing out the problematic vibrations can be tricky.

How Do You Perform the Analysis?

Helicopter vibration analysis involves analyzing the entire helicopter to measure amplitude and phase. Amplitude encompasses the severity of the vibration. Typically, the vibration severity is measured on a scale from 0 to 1.2 IPS (inches per second), with 0 IPS rating as “good,” 1.2 IPS rating as “dangerous,” and a range of ratings in between. Phase is the relationship between peak signal and a reference on the rotor. The change rate in the relationship indicates the presence of critical speed or an imbalance in the rotation’s timing pulse. Vibration balancing equipment can include:

• Dynamic signal analyzers: These analyzers are instruments that measure the vibration amplitude and phase.
• Accelerometer: As the most common type of transducer, the accelerometer is used to measure vibration.
• Velometer: This is another type of transducer, and it measures that instantaneous velocity of vibration.

Each aircraft is unique, and the best methods of helicopter vibration analysis will differ from one aircraft to another. While these are more traditional techniques and instruments used in analysis, advanced sensor technologies are now making spectral analysis possible. In the way that ultrasounds are used in the medical field, these sensors convert vibrations across frequencies into a remotely-monitored signal. With technologies like this developing, it’s essential to keep your aircraft up to date.