Is that as bad as tank weepage gets, left? No, it can get worse and will if it’s not fixed with spot repairs or a reseal. (Photo: Paul Beck.)

the worst idea in aviation design or not nearly as bad as everyone thinks. Mooney has traditionally used them because they’re light and relatively accessible in the design’s single-piece . Other models, such as Piper’s Cherokee, have split wings and/or the fuel cells are accessible and can thus be removable aluminum or bladder- type tanks. Wet wings usually fail somewhat gracefully, beginning with a slight odor of fuel around the airplane or in a i r craft ma i n t e n a n c e the cabin and evidence of blue stains caused by weeping. The condition only grows worse with time. The main failure mode seems to be deterioration of the sealant caused by Reseal: aging and, at least in Mooneys, hard landings. The is attached to the in the area of the tanks Thankless, Expensive and the rubber donuts Mooney gear legs have don’t offer much damping. Years of landings, with a few hard Not many shops will agree to tackle this job, so the ones thrown in, can flex the structure enough to loosen old sealant, kicking skill base is eroding. But there are still choices when off the leak process. (You’ll sometimes tank weepage gets out of control. see bits of sealer when sumping the fuel.) Mooney tanks also develop leaks ne of the unfortunate side SHOPs toward the front of the cells, produc- effects of slow sales Although not many shops take on ing staining visible from inside the Ohas been an erosion in the tank work, two that do are Weep No gear wells. maintenance base. Many smaller More LLC in Minnesota and Florida Minor leaks can be repaired, but shops have disappeared and some of Flight Maintenance, in Venice, Florida. after one or two attempts, a reseal those that remain are either losing Weep No More is an outgrowth of may be the best option. “I usually the ability to do some kinds of work Willmar Air Service in Willmar, base it on the age of the sealant,” says or are just declining to accept it. Minnesota, a long-established and Paul Beck, of Weep No More. “It’s One maintenance procedure on respected Mooney dealer and service pretty much back to the J-model. If the chopping block has been the center. Florida Flight is also a well- you’re back in that vintage, you might resealing or repair of wet fuel known Mooney center based on an want to think about a reseal. If you’re tanks, especially in Mooneys, but in airport with a long Mooney connec- newer than that, you might not need a few other models as well. At best, tion. (Either shop can handle any it,” Beck says. repairing weeping wet-wing tanks is kind of wet wing tank work.) Both Florida Flight and Weep No a dark art, at worst, it’s something Weep No More’s Paul Beck devel- More use a similar strategy to track some owners say they have to have oped his tank sealing process while down leaks. It involves drawing a done several times to stop the leaks, working for Willmar, but now has es- vacuum in the tank, noting where air if even the leaks can be stopped. tablished his own business. He’s also bubbles appear, then spot sealing that There are a few solutions. One is able to travel to the customer—world area. The tank has to be drained to to find a shop that can spot repair wide—to repair spot leaks, but full complete the repair. otherwise sound tanks and back resealing has to be done in his Min- up the work, another is to strip the nesota shop. Florida Flight does all of F ull Reseal tanks back to bare metal and reseal its tank work in Venice. Even well-known Mooney shops like them and a third is simply line the Depending on who you talk to Don Maxwell Aviation in Longview, wet wing bays with neoprene blad- (and how much they’ve recently spent Texas, won’t tackle reseal work, which ders. Each approach has its merits. on tank work), wet wings are either Maxwell describes as the worst job

1 8 • The Aviation Consumer www.aviationconsumer.com February 2012 in aviation. All of the work has to be It’s ugly in there. done through small access panels, Center photo requiring the flexibility of a contor- shows the mess tionist and the patience of a saint. Maxwell does a couple of tank repairs inside a 32-year- a week, but sends reseal work to Paul old Mooney with Beck at Weep No More. original sealant “You just have to find that special being cleaned by guy to do it and I just haven’t found Florida Flight. Ac- him yet. It’s hard on a fat boy to get in cess is through top those positions anymore,” Maxwell jokes. and bottom wing The reseal job requires taking the panels and it’s tank interior down to shiny bare met- slow, tedious work. al then applying fresh sealer, which is Bottom photo shows a itself a three-part process with a day of freshly completed tank curing for each step. It can’t be rushed and haphazard work will bring the seal from Paul Beck’s airplane right back for a fix. (All the Weep No More shop. shops offer warranties of their work.) While he was at Willmar, Beck developed a clever process that sprays Whichever method a stripper called PolyGone into the is used, the cost will be tank cells. PolyGone is a non-corro- similar—a range of $6500 sive, water-soluble solvent specifically to $8000, again, depend- designed for polysulfide sealers. ing on the condition of the old sealer. L ots of Stripper Beck’s process uses hardware sort of Bladders like a purpose-built lawn sprinkler What’s involved with bladders? Essen- to douse the inside of the tank with tially abandoning the wet wing tanks Polygone. Drains at the bottom of and stuffing vulcanized neoprene the fuel cells collect the stripper and bladders through the access panels. loosened sealer and a pump re-circu- For the Mooney, these are available lates the stripper. Tank stripping can up through the J-model and although thus be largely completed automati- they used to exact penalties in both cally in a day or a little longer for reduced fuel and higher empty weight, tanks that have accreted years of a new system from O&N Aircraft patches. Modification retains the J-model’s Other methods include mechani- original 64-gallon capacity at weight cally scraping the old sealer out or penalty of about 30 pounds. This using a combination of both methods, requires eight bags, total, and lists for which is what Florida Flight does. $8000. However, Don Maxwell says he advises customers that bladders and a reseal come out in about the ContaS ct same place pricewise. One good thing is that old systems limited to 54 gal- Don Maxwell Aviation Services lons can get the 10-gallon upgrade for www.donmaxwell.com $2650 list, plus the labor. much payload with full fuel—and you 903-643-9920 Maxwell has done the bladders, but simply don’t trust a resealed wet wing. doesn’t push them. “I usually recom- Otherwise, if you’re going to keep the Florida Flight Maintenance mend that a strip and reseal is best. airplane, a properly done reseal will www.mooneyservice.com They used to have a price advantage enhance the airplane’s value and prob- 941-485-1149 over strip and reseal, but now they’re ably last as long as you own it. You about the same price. Some people can keep the 30 pounds of payload. O&N Aircraft Modifications want the bladders so their local The other side of the same coin is www.onaircraft.com mechanic can take one out and get it that a 30-year-old airplane that hasn’t 570-945-3769 fixed if it leaks. Everyone is used to been resealed but whose logs show ev- bladders,” says Maxwell, who is one of idence of leak fixes should be viewed Weep No More LLC 10 shops that do the O&N bladders. somewhat warily in the pre-buy. Fac- www.weepnomorellc.com Our view is that bladders make tor in the cost of a reseal or bladders 320-295-1671 sense only if you’re not weight criti- because at that vintage, the tanks are cal—in other words, you don’t need holding fuel on borrowed time.

February 2012 www.aviationconsumer.com The Aviation Consumer • 1 9