Preliminary Requirements

Procedure

1. The Maximum Life of a Part (Cycles)

   1. NOTE

      Some given parts have a maximum number of cycles that they can use. These parts are specified in the applicable engine manual.

      Maximum life (cycles)

      1. An Engine Cycle is defined as any flight consisting of one take-off and landing regardless of the length of flight or whether or not thrust reverser is used on landing. Each touch and go is considered an additional cycle.

      2. If it is necessary to use an engine for special extended operations it can cause a change in the cycle life of a part. Engines which are used for pilot instruction can change the cycle life of a part. Engines used during pilot instruction can be put into two groups.

         Group A: Engines used during pilot instruction for less than 10 per cent of their total time each year.

         In this group, the specified cycle as given in step 2.A.(1) can be used.

         Group B: Engines used during pilot instruction for more than 10 per cent of their total time each year.

         In this group, it will be necessary to collect data of the N1 rotor speeds for the average pilot instruction flight profile used by the operator. This data can be collected manually or automatically. Send this data to the International Aero Engines Product Support Department to calculate a cycle for each hour factor for a rotating part. This factor can then be used by the operator to calculate the cycles used for each hour during pilot instruction. For the remaining time for Group B engines, the cycle as specified in step 2.A.(1) is used. At a regular time (approximately 6 months) the N1 rotor speed data collected during subsequent pilot instruction must be sent to the Product Support Department. The cycles for each hour factor can then be calculated again to make sure it has not changed. If a change in the instruction procedure occurs the cycles for each hour factor must be calculated again.

      3. The International Aero Engines Product Support Department will recommend to operators which group their engine will go in. They will also recommend to operators of Group B engines how to collect the correct data and the procedures to follow when the engines in Group B are used.

      4. The cycles used by a rotating part must be calculated before this record is first used. Calculate the cycles used by one of the procedures given as follows:

         1. Do an analysis of records kept before to estimate the total cycles used by each rotating part.

         2. Calculate total cycles

            Total cycles = Total rotating time (hours) / Average flight time (hours)

      5. A record of each cycle must be kept during engine operation. The record of total cycles must be changed for each specified part when it is removed from the engine.

      6. It is permitted to make a physical mark of hours/cycles on the engine parts as an optional procedure in addition to the usual maintenance of permanent records, paper documents, or computer data base records.

         1. To make a cycle identification mark for the total number of cycles on each specified part, use the symbol CYL and an approved permanent mark procedure.

      7. If you install a new specified part during an engine repair before the usual overhaul, make a record of the part as NEW, and record the date of installation. It is permitted to make a physical mark of the symbol NEW and the date of installation on each specified part as an optional procedure in addition to the record of the installation in the permanent records (paper documents or computer data base) for the part.

      8. Parts must not be used after the total cycles for a part has equalled the maximum permitted for that part.