Airline operators are encouraged to evaluate their particular 737NG operating environment,accompanied with debris findings at time of leaning to identify and implement the most effective and economic maintenance interval.

A Airline operators should determine and carry out the most effective and economic maintenance interval after evaluating their particular 737NG operating environment and the debris found when cleaning.

B In order to find the most effective and economic maintenance interval, airline operators have to evaluate and clean the debris accumulated in particular areas of 737NG.

C Before identifying the most effective and economic maintenance interval, airline operators can evaluate the 737NG operating environment by cleaning the debris.