Power Assurance Check (PAC)

Introduction

The Power Assurance Check (PAC) is to be performed each 25 flight hours to ensure the Arrius 2R engine can develop the required minimum specification power in order to meet the manufacturers recommended performance. The engine must pass the PAC in order to achieve the manufacturers performance. Performing the PAC daily is recommended.

The PAC may be performed on the ground, in the hover or in forward flight. To obtain power margin results which are more representative of higher power usage, perform the PAC at a higher aircraft gross weight and/or higher Pressure Altitude. An Automatic PAC (APAC) may be conducted using the Garmin G1000H NXi system, or a Manual PAC (MPAC) may be performed using the applicable charts. APAC or MPAC results provide NG and MGT margins, both of which must be verified to complete a power assurance check. If both the MGT and NG margins are equal to or greater than zero (0), engine performance equals or exceeds minimum specification and the manufacturers recommended performance can be achieved. If any one of these two margins is less than zero (0), engine performance is less than minimum specification and all manufacturers recommended performance cannot be achievable. In order to troubleshoot and restore engine power, refer to Fault Isolation to determine cause of low power.

The Inlet Barrier Filter will accumulate contaminants, particularly in sandy and dusty environments, that can reduce engine performance. Operating with a dirty filter may decrease hover capability by as much as 95 lbs. and climb rate by as much as 170 FPM. When operating in contaminated atmospheric conditions, performance loss should be anticipated and filter cleanings and power assurance checks should be performed more frequently.

If the last performed power assurance check margins are less than 15°C MGT or 0.2% NG, filter cleaning as defined in the helicopter maintenance manual is recommended to restore power, followed by another power assurance check. If subsequent results of power assurance check remain below 15°C MGT or 0.2% NG and flight in contaminated atmospheric conditions is anticipated, more frequent filter cleaning and a power assurance check prior to each flight is recommended.

Automatic Power Assurance Check (APAC) - Ground/Hover

Preliminary requirements

Required Conditions

The parameters that follow are required to obtain accurate APAC results:

Parameter	Condition
Heading	Into wind - 30 KIAS or less
Amperage Indication	35 AMPS or less
Engine Torque	30% Q or above
Measured Gas Temperature	500 - 853 MGT
Gas Producer	83.0 - 101.3% NG

Safety conditions

Failure to maintain the required parameters will be indicated by the CHK LIMITS error message displayed in the PWR CHK window.

Procedure

1. Start the helicopter (BHT-505-FM, Section 2).

Requirements after job completion

Required Conditions