Airworthiness Directive · Amendment 39-19459 · Turbine section
Honeywell International Inc. Turbofan Engines
This AD applies to Honeywell International Inc. (Honeywell) AS907-1-1A turbofan engines with second stage low-pressure turbine (LPT2) rotor blades, part number 3035602-1, installed, that have more than 8,000 hours since new on November 9, 2017 (the effective date of AD 2017-20-06).
We are superseding Airworthiness Directive (AD) 2017-20-06 for certain Honeywell International Inc. (Honeywell) AS907-1-1A turbofan engines. AD 2017-20-06 required a one-time inspection of the second stage low-pressure turbine (LPT2) blades and, if the blades fail the inspection, the replacement of the blades with a part eligible for installation. This AD continues to require a one-time inspection of the LPT2 blades and, if the blades fail the inspection, the replacement of the blades with a part eligible for installation. This AD was prompted by the need to clarify the Applicability and Compliance sections of AD 2017-20-06. We are issuing this AD to address the unsafe condition on these products.
Within 200 hours time in service after the effective date of this AD, do the following:
(1) Perform a one-time borescope inspection for wear of the Z gap contact area at the blade tip shroud for each of the 62 LPT2 rotor blades. Use the Accomplishment Instructions, Paragraph 3.B.(1), of Honeywell Service Bulletin (SB) AS907-72-9067, Revision 1, dated March 20, 2017, to do the inspection.
(2) If the measured wear and/or fretting of any Z gap contact area is greater than 0.005 inch, replace the LPT2 rotor assembly with a part eligible for installation before further flight.
(3) Using a borescope, make a clear digital image of the Z gap contact area at the blade tip shroud of the 62 LPT2 rotor blades, and do the following:
(i) Identify the three Z gap contact areas with the greatest amount of wear and/or fretting.
(ii) Record the blade position on the LPT2 rotor assembly and the measured wear of the three Z gap contact areas with the greatest amount of wear and/or fretting.
(iii) Send the results to Honeywell at engine.reliability@honeywell.com within 30 days after completing these actions.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Engines
