MONTY THE ANSWER MAN ARCHIVE
VENTING CAN BE HARMFUL TO YOUR HEALTH...
I just got around to reading the Swift letter for September. There is something about reading about people and their flying experiences with the Swift that brings back fond memories. Reminiscing about my Swift got me thinking about my airplane and it's unique fuel tank vent system design. Not knowing what has transpired in the way of modifications to the Swifts innards over the past 35 years perhaps I should pass this one on just in case it relates to someone elses airplane.
I think the serial number on Swift N90305 was #314, a GC-1A, but modified by the addition of a larger engine to a GC-1B. Shortly after purchasing the airplane in 1953, I noticed that on a hot day, with full fuel tanks, any movement of the airplane on the ground could cause fuel to siphon through the vent system and drain from the fuselage bottom vent. The only way the siphon could be broken was to raise the tail of the airplane about 4 feet from the ground for several seconds until the flow stopped. I can assure you that this jerk and press operation was a real crowd pleaser at the airport on a Sunday afternoon.
After researching the vent problem I found that there were several venting system designs employed through the build of the Swift. Each change corrected one problem and created another, all in an attempt to get the fuel gauge to read correctly. The one on my airplane, N90305, was supposed to be one of the better modifications made to the system. This information was provided by Temco and the FAA.
The reason that I have provided the above thumbnail information is to create the environment for explaining an incident that could have resulted in what could have been the loss of my airplane. At the time I was working in Florida and keeping 90305 hangared at the New Smyrna Beach Airport. After doing a walk around and pull and jiggle on the airplane I pushed it to the fuel pit and topped off the tanks. It was a beautiful Saturday morning and I intended to do a little sight seeing along the St. Johns River. Before takeoff I turned on my radio and checked it's operation with the airport office. As #305 lifted into the air I turned the radio off since I expected no contacts on a local flight and traffic control didn't exist in those parts. I turned South towards Cocoa Florida but after 20 minutes or so in the hot sun I headed back to the airport. I had glanced at the fuel gauge several times but since I was cruising at reduced power the continued indication of a full tank didn't seem abnormal. However, when I taxied up to the fuel pump the airport operator met me, mentioned something about smoke and began to inspect the underside of #305 explaining that I had trailed a white plume from under the airplane as I left the ground and continued to do so until it disappeared from sight.
He said that he had tried to call me on the radio but I didn't respond. Right then I knew why the fuel gauge had indicated full for so long. A quick look at the fuel gauge indicated just about empty. I calculated that when I landed I had about 10 minutes of flying time left before the engine quit. I figured that I had pumped about 18 gal. of gasoline overboard through the vent system during my 20 minute flight. After a close inspection of the vent system I discovered that muddobbers (wasps) had plugged the opening to the vent located just aft of the rear cabin bulkhead. What appeared to have happened when this vent was the bumping on takeoff had started the siphon through the vent line that is located at the top of the fuel gauge standpipe. This process kept the fuel at the top of the standpipe along with the float that drives the fuel gauge. Of course the reading always indicated at full. The vent line extension through the top of the airplane normally would have prevented the siphon to start, but unfortunately it was plugged.
The next time that #305 went into the air all vent openings were covered with a copper screen guard.
I have no knowledge of any bulletins that were issued about this problem even though I reported it to the FAA at the time. I also have no way to identify the specific system design incorporated in #314 but I suggest that anyone that has the fuel siphon problem, if it hasn't been fixed by now, add a few screens to the vent openings. Something like this could ruin your day. -- Larry Simms (firstname.lastname@example.org)
FUEL STRAINER... (4499)
Bob: Yup, thats the way they were built! Many guys have gotten some aluminum 3/8" tubing (5052 might work best) and with a tubing bender have rearranged the plumbing so they could shut off the fuel, then clean the screen. You also need an aircraft flaring tool (37 1/2 degree) Many are so neatly done it looks like factory. Myself, on the Swift I have now its all stock, so I have to drain the tanks. -- Jim
PS When I mentioned 5052 I was probably remembering replumbing pitot/static lines on a B-707. They were 5052 and bent all right, but were not flared. They used a flareless sleeve and "B" nuts. 5052 might be too hard to get a good flare and dead soft aluminum tubing might be what to use.
LEAKING FUEL DRAIN VALVES...
FUEL STRAINER REMOVAL...
In the spirit of monitoring the frequency, I thought that I better check the record first. Lo and behold, there in the archives was your letter to Bob Runge about the fuel strainer being before the valve. Who'd have thunk such a thing was possible?! Why did they do that? It wasn't that way on my other Swift. I discovered this a day or so before I was planning to bite the bullet and take a day off from work to take the valve out. I figured a 40% disassembly of the Swift should do it. Can you imagine what would have happened to me if I did this and then discovered that it was the plumbing???!!!!!!!! By the way, is there any reason that the strainer assembly can't be moved back about 3" to make it easier to service? Thanks again, and if you're ever near this part of New Jersey I'll buy you some ice cream. -- Dick Aaron N80625, 2405B
BELLY TANKS AND GC...
(Editor's note: Jim is still sans computer as I write this so we'll have Don pinch-hit one more time...)
From: Don Bartholomew <email@example.com>