EASA SIB NE-20-05
Continental Aerospace Technologies 470, 520 and 550 Engines - Camshaft Gear Tooth Fracture
Summary
The Special Airworthiness Information Bulletin SAIB: NE-20-05 is an FAA informational bulletin addressing potential fatigue failure of camshaft gear teeth in Continental Aerospace Technologies 470, 520, and 550 series reciprocating AvGas engines. It highlights the risk of in-flight engine power loss due to fractured camshaft gear teeth and introduces improved camshaft gear part number 656818 as a replacement for older, superseded part numbers. The bulletin applies to engine models O-470-U, IO-470, IO-520, L/TSIO-520, LIO-520, IO-550, IOF-550, TSIO-550, and TSIOL-550.
What Changed
This bulletin informs stakeholders about the availability of an improved camshaft gear, P/N 656818, which has increased thickness to reduce fatigue failures. It recommends inspections of older camshaft gear part numbers 631845, 655430, 655516, and 656031 at 100-hour or annual intervals until replacement with the improved gear at the next engine overhaul. The bulletin does not mandate regulatory action but provides updated service instructions and inspection procedures.
Why It Matters
This information is critical for operators, maintenance personnel, and repair facilities to prevent unexpected engine power loss and forced landings caused by camshaft gear tooth fractures. Regular inspections and timely replacement with the improved camshaft gear enhance engine reliability and safety. Awareness of this bulletin helps ensure continued airworthiness and reduces the risk of in-flight engine failures.
What To Do
Owners, operators, and maintenance personnel should perform inspections of camshaft gear part numbers 631845, 655430, 655516, and 656031 every 100 hours or annually, or at the next maintenance event when accessible. They should replace these older gears with the improved camshaft gear P/N 656818 no later than the next engine overhaul. Repair stations should follow Continental Aerospace Technologies service bulletins CSB05-8D and SB97-6B for inspection and replacement procedures.