DC-9-30 /40 /50 Series (Heavyweight) Aircraft -

    The DHC supplied hardware for the DC-9-30/40/50 series heavyweight aircraft installed under DHC STC ST165CH include the Pratt & Whitney 12-lobe mixer kit (P&W Service Bulletins 5947 & 6146), the five inch extension of the fan inlet guide vanes with the Pratt & Whitney Respaced Inlet Guide Vane kit (RIGV - P&W S/B 5948, et.al.), the modification to the thrust reverser to increase the nozzle exit area (due to the incorporation of the mixer), new CSD tubing for the right hand (number 2) engine, and a forty-degree frangible flap stop. A 20-inch acoustic spacer case is incorporated between the mixer and the thrust reverser for improved mixing and increased sound absorption. To accommodate the extension spacer case, the aft portion of the lower cowling is modified, as is the pylon trailing edge. The nacelle cowling (upper and lower) and pylon apron are modified to provide an integral fit for the RIGV extension. Nose cowl anti-ice tubing elbows and the engine PT2 lines are supplied by DHC to facilitate the extension of the inlet guide vane.

 

    In addition to the hardware supplied as part of the Hushkit, DHC requires as a prerequisite to the installation of the Hushkit (per STC ST165CH) that the following are accomplished:

	Modification of the No. 1 oil damped bearing (P&W S/B 2141)
	Incorporation of acoustic liner material in the fan bypass duct (P&W S/B 4127)
	Replacement of the No. 4 ½ and 6 oil tube assembly (P&W S/B 5465)
	Installation/modification of the stage 1 fan blade with a double chamfer cut (P&W S/B 5897 or 5946 depending on JT8D engine series)
	Modification to the 1st stage fan blade (P&W S/B 6072 - ONLY FOR JT8D-15A ENGINES)
	Acoustically treated nose cowls and thrust reversers (DAC S/B 71-21)
	The ability to operate the aircraft at 40° flaps (OEM provided, DAC S/B 27-202 for DC-9-40/50 series aircraft, or Airborne Express STC SA3846NM for DC-9-30 series aircraft).