V-band couplings—or more simply, the clamps used to secure the engine’s tailpipe to the exhaust housing—are a well-known maintenance concern on turbocharged engines. Like the FAA and NTSB, mechanics have seen plenty of clamp failures over the years, so it’s no surprise that the FAA has adopted AD 2023-09-09, a means to keep a focused eye on potential pipe clamp failures on a variety of turbocharged airplanes and helicopters.
There’s nothing extraordinarily complicated here. The bands are secured with a t-bolt and trunnion mechanism that is either riveted or spot-welded in place, and over time, the spot-weld can generate cracks leading to the failure of the clamp. The clamp can fail prematurely if someone overtorqued the t-bolt. Put it in the category of maintenance-induced failures we consistently read about in wreck reports.