The U.S. Army is inspecting its entire fleet of attack helicopters in an attempt to detect a “critical safety issue.”
The service has detected a number of defective nuts that keep the main rotors attached to the helicopter. The issue has already caused at least one recent accident, which resulted in the death of two pilots.
According to , the part in question is the strap pack nut, which is “the component that keeps the rotor blades from separating from the airframe.” If you think that sounds extremely important to keeping a helicopter in the air, you’d be right. In December 2016, a strap pack nut on a , leading to rotor blade separation. Both aviators onboard died.
The AH-64 Apache helicopter has been the U.S. Army’s main attack chopper for going on four decades now. The Apache has evolved from a dedicated tank killer to a versatile and lethal opponent, providing close air support in Iraq, Libya, and elsewhere. The latest version, the , fields improvements including more powerful General Electric T700 engines, an upgraded transmission, new composite rotor blades, and the Longbow fire control radar.
The problematic nut that's under investigation apparently suffers excessive levels of corrosion and wear from stress, leading to cracks. The problem was thought to be restricted to “severe coastal areas,” presumably areas where salt and water might corrode metal parts. Helicopters were inspected and rinsed down with distilled water to wash away salt. However, the new guidelines for inspecting Apaches includes the entire fleet, regardless of location.
According to an Apache pilot interviewed by Task & Purpose, more than a dozen strap pack nuts on Apaches have been found cracked and dozens more replaced because of unacceptable levels of corrosion or poor condition.
In April, the U.S. Army the latest version of the Apache, the AH-64E, from manufacturer Boeing over concerns about the strap pack nut issue. At the time, Boeing claimed it was testing an improved version of the nut that would eventually go out to the entire Apache fleet, coastal areas first.