Canadian regulators have ordered operators of the Bell 505 light-single to perform urgent checks for cracking in part of the helicopter’s vertical tail that could potentially lead to critical damage to the tail rotor.

In an emergency airworthiness directive (EAD), Transport Canada says there have been “multiple occurrences” of cracking found in the vertical stabiliser top end cap assembly, in some cases leading to the “departure” in flight of components including antennae and the tuning weight.

Bell 505

Source: Bell

Recurrent inspections must be performed every 25 flight hours

“Detailed investigation has identified that the stabiliser top end cap assembly was not designed for the full fatigue spectrum,” says Transport Canada.

It says that if corrective actions are not implemented, components shed as a result of the cracking “could impact and damage the tail rotor, resulting in the loss of directional control of the helicopter”.

Checks of 505s – from 2017-built MSN65011 onwards – are required within 10 flight hours of 29 January, followed by recurrent inspections at intervals of no more than 25h. If cracking is discovered, the part must be replaced, it says.

The EAD has also been adopted by regulators in the USA and Europe.

Bell builds the 505 at its plant in Mirabel, Quebec.