58-01-03: Carburetor Setting

58-01-03 CONVAIR: Applies to the Following Aircraft Equipped With PR-58E5-17 Carburetors in P&W Double Wasp CB16 and 17 Engines; Model 440 Serial 312 Through 420 and All Model 340 With Model 440 Nacelles. Compliance required by first engine overhaul after March 1, 1958, but not later than October 1, 1958. The PR-58E5-17 carburetor setting originally provided in the aircraft has an undesirable leaning tendency. To overcome this deficiency the PR-58E5-29 carburetor setting has been developed and must be incorporated in the above aircraft. Normal fuel metering in carburetors incorporating the PR-58E5-29 "Transport Setting" may result in powers lower than those employed for aircraft certification. This occurs in the high power range with the control in the Auto-Rich position in cases where the carburetor meters on the rich side of the allowable limits. The amount of power loss will vary with different carburetors. Performance information in the FAA approved Airplane Flight Manual is based upon the maximum certificated power ratings of the engine. To obtain full rated power at manifold pressure limits for maximum continuous power, it is necessary to adjust the fuel mixture by the mixture control (takeoff power is not adversely affected by use of the full rich mixture position). (P&WA Engine Operation Information Letter No. 28 covers this subject in further detail.) In order to insure obtaining the power used in aircraft certification, accomplish the following: 1. For MC power during one-engine out operation use Auto-Lean mixture setting. Insert revised pages in the pertinent Airplane Flight Manuals in accordance with Convair Service Bulletins Nos. 340-144A and 440-58. 2. Modify the PR-58E5-17 carburetor setting to the PR-58E5-29 carburetor setting in accordance with Bendix Aircraft Carburetor Service Bulletin No. 820. 3. The Auto-Lean mixture control position should be plainly marked and identified.