Al Schmid:
What is the story on the fuel selector valves used in our planes? My mechanic is telling me that mine is sticking and leaking internally, and is not airworthy.
Editor:
You need to know which model selector valve you have. If it is the old brass Imperial cone-style valve, you should convert to the later Gerdes aluminum valve. The Gerdes valve went into production use sometime during 1973; all the earlier planes were built with the Imperial valve.
Service Instruction SI0364-289 on the Imperial valve requires 100-hour
inspections/Annual inspections for leakage and binding. The SI also spells
out how to service the valve. These valves take a lot of service to remain airworthy. They can be reasonably safe if the pilot understands the valve and can recognize potential failures. When pilots ignore symptoms like binding, they may find themselves airborne looking at the selector handle in their hand, when it snaps off the shaft. If they are really lucky, the valve won’t be between ports, and will still be on a tank with some fuel left in it, when the shaft breaks. If you are lucky (no internal valve damage), your A&P can use the SI (downloadable from BAC) to service your valve.
There was a series of Beech Service Instructions related to replacement of the brass-cone Imperial valve. The list began with SI0622-289, followed by SI0364-289, and finally SI0838-289. In 1977, Beech issued Service Instruction SI0838-289, strongly recommending replacement of the Imperial valve with the Gerdes valve. Since the FAA didn’t mandate it, some owners chose to ignore it. Beech sold the kit for $20, and estimated five hours for conversion labor. Now it is very expensive to convert, compared to the $100 or so when the SI was issued.
If you do already have the newer Gerdes aluminum valve, I sell a kit on BAC to repair the valve (new o-rings and lubricant). The instructions are downloadable from BAC. Or you can mail it to me for repair.
If your plane needs conversion, you’ll need to find a serviceable Gerdes valve. I may have a repaired valve in stock, but it will probably be Wednesday before I’ll know. Any A&P should be able to do the conversion; just minor work with tubing and fittings. As mentioned, the Beech time estimate was five hours. Since your A &P will have to do some minor tube fabrication (not having the kit), it could take a bit longer.