1978 - 1979 928 CIS hard start problems

I'll address a CIS hot start problem that may be difficult to diagnose.  I found this issue with both of my 1979 928s.

The Fuel pressure accumulator is a spring loaded piston in a cylinder that fills with fuel and holds pressure.  If there is a pressure loss in the fuel lines the spring loaded piston pushes pressurized fuel into the lines.  The two functions of the accumulator are to provide fuel pressure at start-up and to keep pressure in the lines to reduce vapor lock (fuel boiling in the lines when the engine is turned off).

The typical failure mode of the fuel pressure accumulator is the piston seal leaks and fuel drips, as long as the fuel leaks are found (or smelled) the diagnosis is simple.  A frozen piston with no leaks is more difficult to diagnose, without the residual pressure hot start problems occur and the most common thought is a fuel pump problem ... however, cold starts are less of a problem thus confusing things.

I replaced the fuel pressure accumulators on both of my 1979 928s.  The part numbers today is 928.110.197.31 (old p/ns: 928.110.197.05 and 928.110.197.07).

Those of you who have flown on early Airbus A32X airliners may have heard what has been described as "the barking dog" strange noises prior to pushback.  The strange noises are the Power Take-off Unit (PTU) hydraulic pressure accumulator charging.  I think the noise has been reduced in newer versions.