By now, it’s probably become evident just how special and impressive helicopters are. While fixed-wing aircraft are impressive in equal measure, there’s something about being able to land almost anywhere you want without the need for a runway that just can’t be beat. This feature, alongside a myriad of others, such as the craft’s ability to adapt to many situations that a fixed-wing plane would have a difficult time adjusting to, has made helicopters one of the go-to aircraft for many fields. From news teams, politicians, and CEOs zooming across cities in a Bell 407 to the military neutralizing a dangerous enemy using the incredibly fast AH-64, these machines can be found almost everywhere. However, this doesn’t mean that they are perfect in every way.
Like many machines, helicopters can experience malfunctions and other equally dangerous issues. Among these is mast bumping, where the rotor hub pivots so much it hits the mast. If you think this sounds bad, it is. A collision between the hub and mast can cause rotor separation, often leading to catastrophic failure. This usually occurs while the helicopter is in the air and usually results in loss of control, potentially causing a crash.
The rotor system is the helicopter’s beating heart
Every helicopter’s secret to flight is the rotor system, which generates lift. The rotor system is also responsible for allowing the helicopter to turn midair, making it one of the most crucial parts of the aircraft. It consists of the mast, a hollow cylindrical shaft that juts from the helicopter’s top hub, the rotor blades, which are the spinning knife-like protrusions we all know and associate with helicopters, and the hub, which is the attachment point where the blades link to the mast.
Of course, there are several rotor systems, each classified according to how the rotor blades are attached. The main ones include semi-rigid rotor systems or teetering rotors, which have two blades attached to the hub, fully articulated rotor systems, where each blade moves independently of the other, and rigid rotor systems, where the blade roots are rigidly mounted to the hub. Each of these systems has its own set of pros and cons. However, mast bumping is heavily (though not exclusively) associated with the first.
The chances of mast bumping are usually low
Mast bumping can occur in almost any helicopter, regardless of whether it’s a military or civilian helicopter. While those with fully articulated and rigid rotor systems are also at risk, those with semi-grid systems are the ones that record the most mast bumping incidents. This is because semi-grid systems feature blades that flap while rotating. While this movement is necessary, it can cause the hub to collide with the mast.
It should be noted, though, that the chances of mast bumping are usually low, especially considering that these helicopters have safety margins designed to reduce the likelihood of such errors occurring. Despite this, factors such as human error, which usually involve poor pilot techniques like abrupt inputs and sideways flight at the helicopter’s maximum speed, and environmental conditions like choppy weather, can lead to mast bumping.
The best way to prevent mast bumping is to fly the helicopter according to training, avoiding low-g conditions as much as possible. Whether you’re in the fastest military helicopter ever built or in a recreational chopper taking in the countryside, it’s important to always stay alert and follow proper procedures when flying.
