our stbd pump failed on our 18
dry seals which then broke down and caused it to leak
http://beechrestorations.wordpress.com/ ... gust-2012/
The Insignificant “s”
Whilst somewhat intriguing this is exactly what it seems – the misreading of a small word could lead to a no start on an engine.
This may not normally be a problem – pilots tend to try one engine and if it does not fire they try the other one. In doing this the pilot of a Beech 18 3N, 3NM or 3TM series
Since starting the Port engine for the first time in May of 2011 the starboard engine has been the focus of our attention.
Up to now all attempts at starting this engine failed—the starter turned the engine over but she failed to catch.
Initially it seemed that fuel was getting to the top cylinders through the priming system but fuel failed to atomize into the cylinders through the carburetor.
The propeller oil leak which was explained in a previous newsletter was cured after fitting a new seal—we were now into diagnosis and fault finding.
There was a school of thought that the starboard carburetor was causing the problem. You may remember we had a similar issue with our Port carburetor.
We had been offered a carb by Andy Foan who operates the Exeter Beech 18 and we had been given a few pointers as to what may possibly be the problem.
Thinking logically it seemed pointless to strip out a carb, fit a new one and potentially be left with exactly the same fault at the end of 4 days of work only to have to repeat the whole process in reverse if it didn’t cure the problem.
A quick check of the fuel system in the Expeditor 3 manual indicated that there was a fuel check valve in the circuit.
The Check valve allows fuel to flow from the tank to the pumps, carbs etc. It is one way and prevents fuel flowing back to the tank—the first thing was to check this as it is easy only consisting of 1 connection from the bulkhead to the fuel pump.
This was disconnected and the system pressurized on the wobble pump—pressure was felt at the pipe end thus testing the correct functioning of the check valve.
Next in line is the fuel pump—fuel was seen to be leaking during attempts to start—the fuel pump seemed to be leaking out of the overflow which discharges to air.
The pump was removed for investigation. Upon disassembly the internal seal was found to be damaged rendering the pump un serviceable.
We did not have a spare pump to hand. A new pump was sourced and fitted the following weekend and again pressure tested—this time the pump did not leak, fuel pressure was maintained indicating to us the fault had been cured.
On the 30th June we prepared for an engine start— we pre-oiled, pulled through and we were ready to try.
Select engine to start, select fuel tank, wobble pump to build fuel pressure, prime 7 strokes engage starter and ignition booster, let it turn 7 blades, switch on magneto—it should fire but it didn’t.
Were back to square one with a possible carb problem.
One of the suggested problems for which we thank both Andy Foan and Rex Ford is an ignition issue. To test this we removed all 9 front spark plugs to check for an ignition source “a shower of sparks”. This shower of sparks is produced by the induction vibrator box located on the engine bulkhead.
We had a spare which Dave examined to understand its operation. He realized that this provided a shower of sparks to the rear set of plugs! I was now into re-installing all of the front plugs and removing rear plugs to establish if we had the correct “shower of sparks” – We did—so we had fuel pressure, a new fuel pump an ignition source what could it be.?
I decided to check one last thing—priming. I disconnected the line at one of the cylinders and got Dave to prump the primer—nothing but air came out—NO FUEL.
We now consulted the Expeditor 3 fuel system circuit diagram. This is when it all became clear. Checking the diagram we could now see that the engine priming system gets its fuel from the left (Port) engine fuel strainer.
What does this mean?
It means that unless you have either the left engine running or at the very least a left fuel tank selected it is impossible to prime the right or Starboard engine!
We selected a port tank – selected right engine on the primer – pumped it and fuel came out. Not just a dribble but a good gout of it.
I re-connected the primer line—pushed the Beech out of the Hangar (well not on my own), went through the starting procedure described earlier and guess what—she literally roared into life and ran very sweetly indeed. We then decided to start the Port engine—History was now being made—history for us anyway as the port engine also came to life.
This was the first time in over thirty years these engines and this aircraft had run on both engines at the same time.
Once we had shut down (this is another issue) we took stock of where we were—I checked the starting procedures for the Expeditor and discovered to my amazement that the procedure in the book was/is very ambiguous and could result in a no start on the starboard engine. It states and I quote “select tanks” select engine to be started—start engine then repeat for port side” – this implies starting of the Starboard engine first which as we discovered is not possible unless you take note of that little insignificant “s” on “select tanks”
Not a nice way to wake up.