EASA SIB 2012-19R1
Uncommanded Engine In-Flight Shutdown triggered by the Tachometer Box
Summary
EASA Safety Information Bulletin SIB No. 2012-19R1 addresses uncommanded engine in-flight shutdowns triggered by the tachometer box on Turboméca ARRIEL 1E2 and ARRIEL 1S1 engines. These engines are installed on Eurocopter Deutschland MBB-BK 117 C-1 and C-2 helicopters, as well as Sikorsky S-76A and S-76C series helicopters. The bulletin provides information on the issue and recommends modifications to improve tachometer box reliability and mitigate shutdown risks.
What Changed
This revision of EASA SIB No. 2012-19 introduces a recommendation to incorporate Eurocopter Deutschland modification K-2725, which installs an improved support to reduce vibration of the tachometer box on MBB-BK117 C-2 helicopters. It also recommends Turboméca modification TU369 to deactivate the simultaneous loss of power turbine sensors (STL) function while maintaining the power turbine overspeed protection, thereby reducing the risk of uncommanded engine shutdowns.
Why It Matters
This information is important for aviation professionals because uncommanded engine shutdowns can compromise flight safety and operational reliability. Implementing the recommended modifications helps operators and maintenance organizations reduce the risk of in-flight engine shutdowns caused by tachometer box malfunctions, ensuring continued safe operation of affected helicopters and engines.
What To Do
Operators of helicopters equipped with Turboméca ARRIEL 1E2 and 1S1 engines should incorporate Turboméca modification TU369 following Turboméca Service Bulletin 292 77 0369. Additionally, operators of MBB-BK117 C-2 helicopters should apply Eurocopter Deutschland modification K-2725 as per ECD Service Bulletin MBB-BK117-C-2-80-001. These recommendations are not mandatory and no compliance deadline is specified.