Tcca Ad Cawis Cracked Cylinders That

An advisory can provide clarification on non- DNDCAF airworthiness circulars when additional guidance regarding an acceptable means of compliance is necessary to consider our unique military airworthiness requirement.

The following is a list of advisories released to date by the TAA.

Failure to do so can lead to fatigue cracks and cause distress to the cylinder head and other rotating parts of the engine.

AV-2007-02 01 February 2007 PRATT WHITNEY (USA) R-985 SERIES ENGINES CYLINDER HEADS AND CYLINDER FLANGES The R-985 engine (Wasp Junior) is an air-cooled, supercharged, 9-cylinder single row radial engine that entered service in 1932 and was later used in thousands of various military aircraft during World War II.

Shortly thereafter, the R-985 engine entered commercial service on the aircraft such as the DHC 3 (Beaver) and the Beechcraft 18 (Expeditor).

Transport Canada Civil Aviation (TCCA) has recently conducted an in-service review to identify the more common defectsfailures and malfunctions associated with the R-985 engine.

A 10-year SDR search clearly identified the three major problems to be (1) cylinder head to cylinder barrel separation (2) cylinder barrel flange cracks (3) crankcase to cylinder barrel hold-down studsnuts.

Although the following FAA Airworthiness Directives were issued some time ago, the mandatory instructions and required actions contained therein remain effective.

FAA AD 56-06-02 was issued to provide maintainers and operators specific technical instructions (Visual and Magnaflux inspections) in order to address problems associated with cylinder barrel flange distortion andor cracks.

This AD also provides guidance and parameters with respect to cylinder flange hold-down studs andor nuts.

PW SB 1000 describe the approved procedure to secure the cylinder flange attaching nuts.

FAA AD 78-08-07 was issued to help detect and prevent separation of the cylinder head and cylinder barrel.

Tcca Ad Cawis Cracked Cylinders That

Inspection of the cylinder assembly (Visual and Ultrasonic inspection) was mandated to detect and then remove cracked cylinders that exceeded specified limits.

Cylinder heads usually fail when the tensile strength of their material has been lowered by excess heat.

Furthermore, the majority of the heat developed within the engine is carried to the atmosphere through the exhaust valve, thus valve timing, seating and clearances must be correct.

If the exhaust valve does not open at precisely the right moment, then the exhaust gases will not leave the cylinder at the right time.

Consequently, heat and internal pressures continue to increase and be transferred to the walls of the combustion chamber and cylinder.

Maintainers and operators should pay frequent attention to the area of the cylinder head cooling fins for exhaust emission stains that could be an indication of a crack developing.

If exhaust deposits are found, wipe clean and monitor closely for cracks.

Oil stains around the area of the cylinder barrel and crankcase could be an indication of a crack.

Additionally, the area of the spark plug bushings and rockerbox area must be monitored for cracks.

Before installing the cylinder assembly onto the crankcase, thoroughly clean the threads of the studs and inspect for looseness and fractures at the base of the threads.

Also check the studs for straightness, nicks, burrs and closely inspect the thread condition of the nuts.

When installing the cylinder assembly to the crankcase mounting pads (power section), make sure to use the approved and specified PWA Handle (referenced in the Wasp Jr.

Tighten the hold-down nuts to the recommended torque; install palnuts (running down finger tight) and then turn over the hold-down nuts.

It is very important that operators properly warm-up and cool-down the engine before and after flight.

It is essential that the cylinder assembly be adequately warmed up in order to heat stretch the cold cylinder, especially before applying high power.