Aircraft with Rolls-Royce (RR) BR700-710 A2-20 engines

ATA 28

Recently, due to an increasing number of failures caused by wiring damage, Rolls-Royce published a revised version of NTO 188 called, “Prevention of Engine Harness Damage.” The wire harnesses installed on the Rolls-Royce BR710 A2-20 engines are not encapsulated, contrary to the ones installed on the Pearl (BR710D5-21) engines. This means that additional precautions need to be taken while performing maintenance tasks on an engine or simply when a Line Replaceable Unit (LRU) is replaced.

During  the General Visual Inspection (GVI) EMM 71-50-00-210-801, these steps should be closely followed:

• Harness clipping points are correctly oriented and secured to prevent hard clashes

• Chafing protection is applied where required

  • Spiral wrap protection may be applied to the engine and EBU harnesses in accordance with EMM 71-50-00-350-803 (BRG3102), in locations where the minimum clearance of 0.50 in cannot be achieved.

• Correct harness tying practice is always applied 

  • Wire harnesses chafing against each other can result in harness damage, if the harnesses are in contact with each other tying chord arrangement can be accomplished in order to physically separate the harnesses from each other. Guidance with regards to tying practices can be found in EMM 71-50-00-960-801 (BRG1700).

In addition to the RR NTO 188, RR NTO 225 is a quick reference guide, providing repair guidance when repairing of the harnesses is required.