The fastener that holds the main rotor to the mast in the Bell Iroquois UH-1 “Huey” helicopter was called the Jesus Nut by helicopter pilots and their passengers in Vietnam. Given that if anything went wrong with this nut in flight, the rotor would go spinning off to an unknown destination and the helicopter left behind would take on the aerodynamic properties of a brick, it is an apt name. Everyone aboard depended on that simple threaded nut for their safety. Modern helicopters may or may not depend on a single fastener to keep their rotors firmly affixed to their mast. If they do not, there are many fasteners whose ability to stay in place in flight is just as important.
Helicopter maintenance demands precision torque tools. Most modern helicopters are powered by jet turbines. Every fastener and bolt that holds the fan blades and the engine housing in place must be tightened to exact specifications. If they are left loose, one may come free in flight and do catastrophic damage to the parts of the engine rotating at high speed. If they are tightened too far, then they may place stress on housings and cause them to crack during the pressures and vibrations of flight. A quality set of torque tools is essential for doing preventative maintenance on helicopters and repairing damaged ones.
Why Torque Control Matters for Helicopter Maintenance
The powerful jet engines that power helicopters are attached to shafts that turn both the main and rear rotors. This means a lot of weight and equipment spinning at very high speeds inside the airframe. Everything that is spinning or attached to something that is spinning needs to be fastened precisely to the specifications set out by the helicopter’s manufacturer. If it is not, pieces may come free with incredible force, or pieces that are over compressed and under strain may break. It isn’t enough to simply feel that a bolt or screw is properly tightened; whether a helicopter maintained this way returns from its flight is in the hands of fate.
Repairing helicopter controls also demands precision. Whether the control arrangement gives the pilot and the co-pilot individual collective controls or a T-stick array where each pilot is connected to a single center collective, each move of the collective moves an array of complicated control linkages that connect to a swashplate at the base of the mast. The swashplate, in turn, is linked to rotors and controls their pitch. If any of these attachments are too loose or tight, then the controls won’t move correctly and the helicopter’s safety becomes questionable. The key to properly maintaining and repairing helicopters is precisely tightened fasteners with torque measured to spec.
Choosing the Right Torque Tools for Repairing Helicopters
Aviation bolts and screws are torqued specifically to distribute loads as designed by the manufacturer. Their type and the manufacturer’s recommended torque setting can usually be found in the helicopter’s maintenance manual. Properly tightened torque bolts are important for all aircraft, and our illustrated guide to reading aircraft torque bolts will help you understand maintenance diagrams. However, complying with the manufacturer’s setting requires the proper tools. Torque wrenches, torque screwdrivers, and precisely calibrated power assembly tools are the best tools to use when repairing helicopters and conducting preventative helicopter maintenance.
The heavy-duty bolts for helicopter engines or transmissions and screws on airframes require exact tightening to specifications. Pulse tools are great when working with multiple heavy bolts with the same specifications. On the other hand, air screwdrivers with auto shut-off are ideal for the numerous lighter weight screws on the airframe. They speed up repetitive assembly and disassembly, reduce the fatigue of the mechanic, and deliver precise torque control throughout the process.
Mechanical systems like the interiors of engines, power transfer systems, and transmission rebuilds have more variable torque settings. As such, these situations call for adjustable hand operated torque screwdrivers and torque wrenches. These tools signal when the operator is approaching the set torque limit, but not all of them actively prevent the operator from exceeding those limits. Click wrenches warn the operator they’re approaching the torque limit with a click but do not stop them from exceeding it. Helicopters are especially sensitive to over-torquing, so cam-over wrenches and breakover wrenches that physically stop the user from over-tightening are a better choice for helicopter maintenance.
The smaller, precise world of helicopter controls and control linkages requires more exactly measured amounts of torque. Dial torque screwdrivers and adjustable torque screwdrivers are the best options for precisely adjusting and monitoring the torque applied to the fasteners that hold helicopter control linkages together. Both types have memory functions so that quality control personnel can verify that everything is functioning properly.
High-quality torque tools keep pilots in control of the aircraft with a precision equal to the quality of the maintenance work and repairs done to the helicopter. Torque tools are critical for ensuring that helicopter maintenance is done correctly and to the specifications mandated by the manufacturer. After all, leaving the tightening of helicopter fasteners to feel puts the helicopter and the lives of those flying on it at risk.
