Service Bulletin No. Н5ТЛ-001БЭ


Engine АИ-25ТЛ

SUBJECT: Information for Operators and Maintenance and Repair Organizations about the effective life limits and procedure for their approval during on-condition operation
of АИ-25ТЛ engines powering demilitarized L-39 aircraft with civil registration

1. This Service Bulletin covers new and overhauled АИ-25ТЛ engines powering demilitarized L-39 aircraft with civil registration.

2. The engine Designer (Ivchenko-Progress SE) and Manufacturer (Motor Sich JSC) hereby inform Operators and owners of L-39 aircraft, as well as certified Maintenance and Repair Organizations, that the following service and calendar life (both
storage and operation) limits has been assigned for new and overhauled АИ-25ТЛ
engines, their accessories and component parts:
2.1. Engine total service life is:
– 4000 hours, 6000 cycles.
Total service life of rotor parts is as follows:
– 1st stage turbine 0150402002-05 rotor blade (25Т.04.02.002-05) – 2000 hours,
3000 cycles;
– rolling element bearings of АИ-25ТЛ engine – 4000 hours (among them,
5-2113Б1Т3, А2113Б1Т3 and А2113Б1Т3 roller bearings – 1500 hours).
2.2.1. Service life to first overhaul is as follows:
– 300 hours for engines with S/N 9052523300001 and above;
– 400 hours for engines with S/N 9052523300072 and above;
– 500 hours for engines with S/N 9052521700001 and above;
– 750 hours for engines with S/N 9052522100001 and above;
– 1000 hours for engines with S/N 7082524400001 and above.
2.2.2. Service life between overhauls is according to the engine Log Book.
2.3. Calendar life (both storage and operation) to first overhaul and between overhauls is as follows:
– up to 25 years based on technical condition, with periodical approval by Designer or Manufacture of the engine (hereinafter referred to as Work Performer) of capability to continue operation of the engine.

NOTE: Some АИ-25ТЛ engines with expired calendar life (25 years) that have an unused residual service life in terms of hours and cycles, may get permission from the engine Designer to further operate the engine in the absence of critical remarks on engine operation and under positive results of its technical condition assessment having been done with direct involvement of specialists (experts) of the engine Designer in accordance with the “List of works on assessment of АИ-25ТЛ engine technical condition” (Appendix 1).

3. Engine technical condition assessment required to confirm its capability to continue operation within service life limits (hours/cycles) specified in the operational documentation after expiry of the previously assigned calendar life specified in the engine Log Book shall be performed at yearly intervals.

The assessment shall be done on the basis of contracts with Operators and jointly by specialists of Operators and specialists (experts) of the Work Performer at the premises of PART-145-certified Maintenance and Repair Organizations in accordance with the “List of works on assessment of АИ-25ТЛ engine technical condition”.

NOTE: In some cases, depending on engine operation/storage peculiarities, interval between engine technical condition assessments may be increased up to 2 (two) years based on terms and conditions stipulated by a contract between the Operator and Work Performer.

4. In some cases, Ivchenko-Progress SE may transfer the right to perform the engine technical condition assessment to a certified Maintenance and Repair Organization on a contractual basis. In this case, a technical report (Appendix 2) drawn up based on the results of such assessment shall be sent to Ivchenko-Progress SE for analysis and approval.

NOTE: Requests for conclusion of contracts for assessment of АИ-25ТЛ engine technical condition shall be sent to the address of Ivchenko-Progress SE:
e-mail: 03529@ivchenko-progress.com or ovs@ivchenko-progress.com, tel. (fax): +38-0612-65-57-88 or +38-0612-65-61-05.

5. The following engines are also subject to assessment of their technical condition in order to confirm their capability to continue operation within the set limits of service life in hours and cycles, provided the requirements to storage specified in the АИ-25ТЛ engine Maintenance Manual are followed:
– ones with zero operating time accumulated after overhaul or new ones that were
stored in the original package in depot (or in a hangar) for maximum 12 years (except for tropical climate);
– ones previously removed from the aircraft due to expiration of calendar life and stored in preserved condition in depot (in a hangar) for maximum 3 years;
– ones stored as part of the aircraft in preserved condition with periodic re- preservation.

6. The sequence of works on assessment of engine technical condition is as follows:
6.1. The Operator, in advance to the presumed date of expiration of previous capability confirmation period, shall send to the address of Ivchenko-Progress SE a request to perform the works for confirmation of engine capability to be operated during subsequent period, having indicated at that:
– the name of Operator and the name of its manager;
– postal address with indication of post office, telegraph call sign or fax number, E-mail address, etc.;
– bank account details (if necessary to conclude a contract for performance of works on confirmation of engines capability to continue operation);
– engine serial number;
– engine accumulated operating time in hours and cycles – since new and after last overhaul;
– the date of engine manufacture and the date of last overhaul;
– number of overhauls and the name of organization that performed the last overhaul;
– service life assigned at manufacture and at the last overhaul;
– date of engine installation into the aircraft;
– who, when and to what extent performed the works on confirmation of engine capability for its previous period of operation;
– date of preservation of the engine stored in preserved condition – as part of the aircraft or in depot;
– number of the aircraft in which the engine is installed;
– region of operation;
– date and place of performance of works.

Note. To validate the engine authenticity, the Operator, at the first stage of confirmation of engine capability to continue operation, shall send the copies of the following pages of the engine Log Book:

– title page;
– ”Acceptance certificate” (at engine manufacture, section 7);
– ”Acceptance certificate“ (after last overhaul, section 15.3);
– copy of the last page from section 10 ”Service record“ with specification of total operating time in hours, cycles, as well as time of operation at nominal and takeoff power ratings;
– copy of the last page from section 6.2 ”Changes in time limits”.

6.2. After receiving the request and having analyzed the engine operating conditions, Ivchenko-Progress SE (or Motor Sich JSC at the instruction of Ivchenko- Progress SE) shall send its specialists for performing, together with the Operator, the
works as per the ”List of works on assessment of АИ-25ТЛ engine technical condition“. If the results of the works are positive, the specialists of the Operator and of Ivchenko- Progress SE (Motor Sich JSC) shall draw up a joint technical report in three copies.

6.3. If the works are performed with the participation of Motor Sich JSC specialists, a copy of the technical report approved by the Operator Manager shall be sent by E-mail (the address is given above in item 4 of this Service Bulletin) to Ivchenko-Progress SE for analysis and approval. In case of positive results of the analysis, Motor Sich JSC shall send by E-mail to the address of Operator the technical report approved by Inchenko-Progress SE Chief Designer, as well as the written notification with confirmation of the engine capability to continue operation. Having received the technical report in electronic form and the written confirmation, the Operator shall make an entry in section 6.2 of the engine Log Book about the engine capability to continue operation during the next period according to conclusions of the
technical report.

6.4. If the works are performed with the participation of Motor Sich JSC specialists, the entry about the engine capability to continue operation shall also be confirmed by pasting of a numbered holographic protective element into section 6.2 of the engine Log Book.

6.5. When the works are performed with the participation of Ivchenko-Progress SE specialists, three original copies of the technical report approved by the Operator Manager shall be sent to Ivchenko-Progress SE for approval by its Chief Designer. The entry in the engine Log Book and the technical report approved by Chief Designer and affixed with the seal of Ivchenko-Progress SE are regarded as the basis for establishment of the next period of the engine capability to continue operation.

7. Step-by-step confirmation of capability of the engine, as well as accessories and vendor items mounted in the engine to continue operation is performed simultaneously with confirmation of capability of the engine without regard to the total calendar lives indicated in the certificates of some accessories. The calendar lives of vendor items, increased as per technical condition, shall not exceed the limit value of calendar life of their engine by more than three years. Replacement of accessories and vendor items, in case of their failure during on-condition operation, shall be done from the stock and at the expense of the Operator.

8. In come cases, in order to avoid the aircraft out-of-service time, before arrival of Ivchenko-Progress SE (Motor Sich JSC) specialists and in the period of formalisation of technical reports after performance of works, it is permitted, by agreement between the Operator and Ivchenko-Progress SE, to temporarily operate the engine up to three months longer than previously agreed period duration.

9. The engines, their accessories and vendor items for which, in the course of assessment of their technical condition, non-satisfactory results were obtained or those having not worked out the set period, shall be removed from operation free of claims.
Note. Depending on the nature of damage revealed, it is possible to restore the engine serviceability at the premises of certified Maintenance and Repair Organizations by means of replacement of failed modules by good ones according to the АИ-25ТЛ engine light overhaul manual on a contractual basis with Ivchenko-Progress SE or Motor Sich JSC.

In some cases, by agreement with Ivchenko-Progress SE and Motor Sich JSC, it is
permitted to use parts (modules) from so-called ”donor“ engines, i.e., the engines prepared for dispatching to overhaul and completed with the parts (modules) having satisfactory technical condition and necessary residue of service life in terms of hours and cycles.

10. Operation of АИ-25ТЛ engines, their accessories and vendor items with confirmed capability to continue on-condition operation shall be performed according to the following operating and maintenance documentation for АИ-25ТЛ engine:
1. ”АИ-25ТЛ aircraft by-pass turbojet engine. Book One. Technical description. Revision IV”.
2. ”АИ-25ТЛ aircraft by-pass turbojet engine. Book Two. Maintenance Manual.”
3. ”Aircraft Bypass Turbojet Engine АИ-25ТЛ. Maintenance Manual“, as well as operating and maintenance documentation for L-39 aircraft.

Note. The above mentioned operating and maintenance documentation for АИ-25ТЛ engine, refined by all the Service Bulletins with code ”БЭ“ effective at the date of receipt of the request, as well as Parts catalog, other Service Bulletins, etc. are supplied by Motor Sich JSC on requests of Operators, air transport enterprises and Maintenance and Repair Organizations on a contractual basis.

The requests are to be sent to the address:
e-mail: service@motorsich.com or vtf@motorsich.com, tel. (fax): +38-061-720-50-33 or + 38-0612-65-58-85.


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