Remarks: The compliance of this AD must be recorded in Aircraft Logbook, where applicable the requirements of this AD must be integrated into Aircraft Technical Documentation. Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyne Airport, 160 08 Prague 6, Czech Republic, tel: 420 2 33320922, fax: 420 2 20562270.

Inspection of high pressure turbine front rotating air seal (FOS) (ATA 72)

This Airworthiness Directive applies to CFM56-2, CFM56-3-B1, CFM56-3B-2 and CFM56-3C-1 turbofan engines which HPT FOS serial number starts with NCE [see detail in appendix 1 of SB 72-869 dated November 12, 1999 (or later revision) in appendix 1 of SB 72-922 dated November 12, 1999 (or later revision)].

On a CFM56-3 a HPT front rotating air seal separation caused an uncontained engine event. A crack started from damage that occurred during the manufacture of one bolt hole. The cause of the damage is the use of machining parameters/processes outside of the range required for manufacture. The affected parts were produced by the same machining source.

- Perform an eddy current Inspection of the HPT front rotating air seal to identify any bolt hole anomalies, respecting method, dates and cycles since new (CSN) indicated in CFM56-2 SB 72-869 dated November 12, 1999 and CFM56-3/-3B/-3C SB 72-922 dated November 12, 1999,

- Remove from service parts found with cracks,

- No later than 30 days after the inspection, report the result to CFM INTERNATIONAL using the certificate of conformance attached to the SB.

REF.: Service Bulletin CFM56-2 72-869 dated November 12, 1999

and CFM56-3/-3B/-3C SB 72-922 dated November 12, 1999

EFFECTIVE DATE: ON RECEIPT FROM JANUARY 12, 2000