AD 2017-06-03 Airworthiness Directives; Meggitt (Troy), Inc. Combustion Heaters

Makes named: cessna, piper, beech. Read the applicability below — it usually turns on serial or part numbers too.

(1) This AD applies to Meggitt (Troy), Inc. (previously known as Stewart Warner South Wind Corporation and as Stewart Warner South Wind Division) Models (to include all dash number and model number variants) 921, 930, 937, 940, 944, 945, 977, 978, 979, 8240, 8253, 8259, and 8472 combustion heaters that: (i) Are installed on, but not limited to, certain Beech, Britten-Norman, Cessna Aircraft Company, and Piper Aircraft, Inc. airplanes; and (ii) certificated in any category.

Comply with this AD by doing one of the actions in paragraphs (f)(1), (2), or (3) of this AD at the compliance times indicated, unless already done. If the hours of combustion heater operation cannot be determined, use 50 percent of the airplane's hours time-in-service (TIS): (1) Perform the actions specified in paragraphs (g) through (j) of this AD; (2) Disable the heater following the instructions in paragraph (k)(1) of this AD; or (3) Remove the heater following the instructions in paragraph (k)(2) of this AD.

Within the next 10 hours TIS of the combustion heater after May 5, 2017 (the effective date of this AD) or the next scheduled 100-hour inspection, annual inspection, or phase inspection that occurs 30 days after May 5, 2017 (the effective date of this AD), whichever occurs first, and repetitively thereafter at intervals not to exceed 250 hours of combustion heater operation or two years, whichever occurs first, do the following inspections and PDT listed in paragraphs (g)(1) through (4) of this AD. You may do one of the actions in paragraph (k)(1) or (2) of this AD in lieu of doing the inspections required by paragraph (g). (1) Inspections using the instructions in paragraph (i)(1) or (j) of this AD, as applicable. (2) Inspections using the steps listed in paragraphs (g)(2)(i) through (v) of this AD: (i) Inspect the thermostat switch (external from heater) and upper limit switch (located on the heater). In cold static condition, both switches should be in closed position; in operation (hot) condition, both switches should regulate their sensed temperatures within ± 10 degrees F. (ii) Inspect the solenoid valve and fuel pump for fuel leak, corrosion, diaphragm crack, metal shavings, and excess grease. (iii) With the heater operating, inspect the fuel pump output pressure for proper gauge hook up and pressure range readings. (iv) Inspect the combustion heater's fuel pump operating pressure to assure it is not affected by other on-board pumps. (v) Inspect the heater to assure it instantly responds to the on/off switch. (3) Installation inspections and checks using the steps listed in paragraphs (g)(3)(i) through (iv) of this AD: (i) Inspect ventilating air and combustion air inlets and exhaust outlet correcting any restrictions and ensure attachment security. (ii) Inspect drain line and ensure it is free of obstruction. (iii) Check all fuel lines for security at joints and shrouds, correcting/replacing those showing evidence of looseness or leakage. (iv) Check all electrical wiring for security at attachment points, correcting conditions leading to arcing, chafing or looseness. (4) Pressure decay test using the instructions in paragraph (i)(2) or (j) of this AD, as applicable.

This AD was prompted by an airplane accident and reports we received that the combustion heater was malfunctioning. We are issuing this AD to detect and correct a hazardous condition caused by deterioration of the combustion heater, which could lead to ignition of components and result in smoke and fumes in the cabin.

This AD replaces AD 81-09-09, Amendment 39-4102 (46 FR 24936, May 4, 1981).