NPA OPS-38, ACJ-1 to Appendix 1 to JAR-OPS 3.517(a)

1. Helicopter operations without an assured safe forced landing capability –Powerplant reliability statistics • NPA OPS-38, ACJ-1 to Appendix 1 to JAR-OPS 3.517(a) • Helicopter operations without an assured safe forced landing capability • 1. As part of the risk assessment prior to granting an approval under Appendix 1 to JAR-OPS 3.517(a), the Authority should consider appropriate powerplant reliability statistics available for the helicopter type and the engine type. • 2. Except in the case of new engines, such data should show sudden powerloss from the set of in-flight shutdown (IFSD) events not exceeding 1 per 100,000 engine hours in a 5 year moving window. However, a rate in excess of this value, but not exceeding 3 per 100,000 engine hours, may be accepted by the Authority after an assessment showing an improving trend. • 3. New engines should be assessed on a case-by-case basis. • 4. After the initial assessment, updated statistics should be periodically reassessed, and any adverse sustained trend will require an immediate evaluation to be accomplished by the Authority in consultation with the operator and the manufacturers concerned. The evaluation may result in corrective action or operational restrictions being applied.

2. Helicopter operations without an assured safe forced landing capability –Powerplant reliability statistics • Proposed way ahead for harmonisation : • Calculation by the engine manufacturer of the engine sudden power loss rate : see TURBOMECA proposed methodology, • Calculation by the helicopter manufacturer of the powerplant sudden power loss rate (caused by the engine + the engine installation)

3. Helicopter operations without an assured safe forced landing capability –Powerplant reliability statistics • Proposed methodology for calculating a “powerplant power loss rate”: • Take into account all engine-caused events as defined by the engine manufacturer in the “engine power loss” documents, • Take into account all events caused by the helicopter installation (including the helicopter maintenance where the applied maintenance was compliant with the Maintenance Manual), • Exclude the events from uncertain source, for which the helicopter has not been investigated, or the events assigned to the unsuitable or non-representative use (operation or maintenance) of the helicopter,

4. Helicopter operations without an assured safe forced landing capability –Powerplant reliability statistics • Proposed methodology for calculating a “powerplant power loss rate” (continued): • For the events assigned to the helicopter installation, where the helicopter installation has been submitted to investigation which did not allow to define a presumed cause, the applicability factor is arbitrarily fixed at 50 % • Corrective actions, if defined by the helicopter manufacturer in a minimum required helicopter modification standard, can be taken into account in the powerplant power loss rate by applying an applicability factor lower than 1 (reliability improvement factor) to the concerned event.