AD 2017-14-04

For any oil cooler hose assemblies that do not meet TSO-C53a, Type D requirements: Within the next 100 hours time-in-service (TIS) after February 5, 1996 (the effective date retained from AD 95-26-13), and repetitively thereafter at intervals not to exceed 100 hours TIS, inspect the fire sleeve of each oil cooler hose assembly for soaked oil, a brownish or whitish color, and any evidence of brittleness or deterioration as a result of heat or oil seepage. See figure 1 to paragraphs (g) and (h) of this AD for additional information.

Note 1 to paragraphs (g) and (h)(1) of this AD: Although not required by this AD, the FAA recommends that an oil cooler hose assembly flexibility test be done at 100-hour TIS intervals by gently lifting each oil cooler hose assembly in several places along its bottom surface, ideally at the center of an arc. If the oil cooler hose assembly moves slightly, either from side-to-side or upward, then some flexibility remains. If the oil cooler hose assembly appears hardened or inflexible, replacement is recommended.

(1) For any oil cooler hose assemblies that do not meet TSO-C53a, Type D requirements: Within the next 100 hours TIS after February 5, 1996 (the effective date retained from AD 95-26-13), and repetitively thereafter at intervals not to exceed 100 hours TIS, inspect the fire sleeve of each oil cooler hose assembly for soaked oil, a brownish or whitish color, and any evidence of brittleness or deterioration as a result of heat or oil seepage. See figure 1 to paragraphs (g) and (h) of this AD for additional information.

(2) For any oil cooler hose assemblies that do not meet TSO-C53a, Type D requirements: Within the next 100 hours TIS after February 5, 1996 (the effective date retained from AD 95-26-13) and repetitively thereafter at intervals not to exceed 100 hours TIS, inspect the oil cooler hose assemblies to ensure the installation conditions in paragraphs (h)(2)(i) through (iii) of this AD are met. See figure 1 to paragraphs (g) and (h) of this AD for additional information. If the conditions listed in paragraphs (h)(2)(i) through (iii) of this AD are not met, before further flight, make any necessary adjustments. See figure 2 to paragraph (h)(2) of this AD for additional information.

(i) The oil cooler hose assemblies pass underneath and behind the electrical ground cable and in front of the lower of the two engine mounts.

(ii) The oil cooler hose assemblies are secured to the engine mount strut and a clearance of at least 2 inches exists between the oil cooler hose assemblies and the exhaust stack.

(iii) Oil cooler hose assemblies with a minimum outer diameter of 0.75 inch are installed with a bend radius of at least 6.5 inches.

(1) If any of the conditions described in paragraph (g) or (h)(1) of this AD are found on an oil cooler hose assembly during the inspection required in paragraph (g) or (h)(1) of this AD, as applicable, before further flight, replace the oil cooler hose assembly with a serviceable new or used TSO-C53a Type D oil cooler hose assembly or TSO-C53a Type C oil cooler hose assembly. If a used TSO-C53a Type C oil cooler hose assembly is installed, it must have documented hours TIS.

Note 2 to paragraphs (i)(1) and (j) of this AD: If only one of the two oil cooler hose assemblies requires replacement, the FAA recommends replacing both of the oil cooler hose assemblies to simplify tracking the hours TIS of the assemblies.

(2) If a newly installed oil cooler hose assembly is a TSO-C53a Type C oil cooler hose assembly and it is mounted in a location other than at or aft of the rear of the engine, then replacement of the oil cooler hose assembly must meet the conditions listed in paragraphs (h)(2)(i) through (iii) of this AD.

(3) If compliance with paragraphs (i)(1) and (i)(2) of this AD results in both oil cooler hose assemblies of an airplane meeting TSO-C53a Type D requirements, then the requirements of this AD are terminated for the airplane.

(1) When a TSO-C53a Type C oil cooler hose assembly accumulates 8 years or 1,000 hours TIS, whichever occurs first, replace the oil cooler hose assembly with a serviceable new or used TSO-C53a Type D oil cooler hose assembly or TSO-C53a Type C oil cooler hose assembly. If a used TSO-C53a Type C oil cooler hose assembly is installed, it must have documented hours TIS. If the newly installed oil cooler is a TSO-C53a Type C oil cooler hose assembly and it is mounted in a location other than at or aft of the rear of the engine the installation must meet the conditions listed in paragraphs (h)(2)(i) through (iii) of this AD.

(2) You may at any time before a TSO-C53a Type C oil cooler hose assembly exceeds the life limit in paragraph (j)(1) of this AD, replace a TSO-C53a Type C oil cooler hose assembly with a TSO-C53a Type D oil cooler hose assembly.

(3) If compliance with paragraphs (j)(1) or (j)(2) of this AD results in both oil cooler hose assemblies of an airplane meeting TSO-C53a Type D requirements, then the requirements of this AD are terminated for the airplane.