Airworthiness Directive · Amendment 39-17511 · CFM International, S. A. Turbofan Engines
CFM International, S. A. Turbofan Engines
This AD applies to CFM International S.A. (CFM) model CFM56-5 and CFM56-5B series turbofan engines with any of the hydro-mechanical unit (HMU) fuel control part numbers (P/Ns) in paragraphs (c)(1) and (c)(2) of this AD, installed:
(1) CFM56-5: CFM P/Ns 1348M79P02; 1348M79P03; 1348M79P04; 1348M79P06; 1348M79P07; 1348M79P08; 1348M79P09; 1348M79P10; 1348M79P11; 1348M79P12; 1348M79P13; and 1348M79P14.
(2) CFM56-5B: CFM P/Ns: 1348M79P08; 1348M79P09; 1348M79P10; 1348M79P11; 1348M79P12; 1348M79P13; and 1348M79P14.
We are adopting a new airworthiness directive (AD) for certain CFM International, S. A. (CFM) model CFM56-5 and CFM56-5B series turbofan engines. This AD was prompted by corrosion of the delta-P valve in the hydro-mechanical unit (HMU) fuel control caused by exposure to type TS-1 fuel. This AD requires cleaning, inspection, and repair of affected HMUs. We are issuing this AD to prevent seizure of the HMU, leading to failure of one or more engines and damage to the airplane.
Unless already done, do the following:
(1) From the effective date of this AD, record all TS-1 fuel usage.
(2) If the HMU never uses TS-1 fuel, no further action is required.
If the HMU has operated on TS-1 fuel, inspect the HMU for corrosion as follows:
(1) For an HMU that has operated for fewer than 6,000 hours since new (HSN) or hours since last overhaul, inspect the HMU before 10,000 HSN or hours since last overhaul, whichever comes later.
(2) For an HMU that has operated for 6,000 or more HSN or hours since last overhaul, inspect the HMU within 24 months or 4,000 hours after the effective date of this AD, whichever comes first.
(3) Use paragraph 3.A(2) of CFM Service Bulletin (SB) No. CFM56-5 S/B 73-0182, Revision 6, dated March 8, 2012, or CFM SB No. CFM56-5B S/B 73-0122, Revision 8, dated March 8, 2012, to do the inspection.
Repeat the inspection required in paragraph (g)(3) of this AD before 10,000 hours since last overhaul if, after last overhaul, the HMU is exposed to TS-1 fuel.
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.
