77-01-03 PIPER AIRCRAFT CORPORATION: Amendment 39-2801. Applies to Model PA-28-151 airplanes, serial numbers 28-7415001 through 28-7715278 and 28-7715289 certificated in all categories. \n\n\tCompliance required within the next 10 hours' time in service after the effective date of this AD, unless already accomplished. \n\n\tTo detect and correct those carburetor air filter boxes that do not contain a drain hole, accomplish the following: \n\n\t(a)\tOpen the top right side engine cowl door to gain access to the carburetor air filter box, Piper Part Number 35462-00, at the right hand bottom section of the engine compartment. \n\n\t(b)\tCheck visually and by feel to determine whether the carburetor air filter box contains a drain hole in the lower rear corner of the outside half of the carburetor air filter box. (See figure) This check may be performed by the pilot. \n\n\n\nAD 77-01-03 \n\n\t(c)\tIf the box contains a drain hole, accomplish (f). \n\n\t(d)\tIf the box does not contain a drain hole, accomplish (e) and (f). \n\n\t(e)\tModify the carburetor air filter box as follows: \n\n\t\t(1)\tRemove and disassemble the carburetor air filter box. \n\n\t\t(2)\tDrill a .19 inch diameter hole in the lower rear corner of the outside half of the carburetor air filter box. (See figure) \n\n\t\t(3)\tReassemble and reinstall the carburetor air filter box. \n\n\t(f)\tClose the engine cowl and return the airplane to service. \n\n\tPiper Service Bulletin 536 also pertains to this subject. \n\n\tThis amendment becomes effective January 14, 1977.