---------------------------------------------------------- Yak-List Digest Archive --- Total Messages Posted Fri 05/03/13: 7 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:08 PM - yak 55 engine surge, in flight (Epistaxis) 2. 04:47 PM - Re: yak 55 engine surge, in flight (Roger Kemp M.D.) 3. 06:21 PM - Re: yak 55 engine surge, in flight (Javier Carrasco) 4. 06:45 PM - Re: yak 55 engine surge, in flight (Epistaxis) 5. 07:05 PM - Front Gear Level (CJ6) (Thomas Geoghegan) 6. 07:17 PM - Re: Re: yak 55 engine surge, in flight (Roger Kemp M.D.) 7. 07:33 PM - Re: Front Gear Level (CJ6) (Roger Kemp M.D.) ________________________________ Message 1 _____________________________________ Time: 04:08:31 PM PST US Subject: Yak-List: yak 55 engine surge, in flight From: "Epistaxis" Hello, have a Yak55 which just presented with an engine or prop surge, after doing moderate acro. Initial indication was a rapid loss in performance. After throttle back, settled down to a constant surge. Fuel pressure was good and constant,have checked the entire fuel system everything is clean and clear. Can`t duplicate the problem on the ground during runup. But did surge again on next test flight. Would like to know if the aneriod diaphragm or the larger pressure diaphragm were failing could cause this, although no garbage was found in the carb screens. Or should I focuse on the prop and governor. Governor screen is clean as well. Has anybody run across this situation? Thanks Read this topic online here: http://forums.matronics.com/viewtopic.php?p=399918#399918 ________________________________ Message 2 _____________________________________ Time: 04:47:09 PM PST US Subject: Re: Yak-List: yak 55 engine surge, in flight From: "Roger Kemp M.D." Have had the aneroid diaphragm cause surging and have had engine failure at 100% T.O. Power due to a flapper in the fuel line that broke off and blocked the carb fuel screen. With the flapper the surge was intermittent at high power settings. It improved with power reduction. The diaphragm was most noticeable at 5000 to 6000 ft. Doc Sent from my iPad On May 3, 2013, at 6:06 PM, "Epistaxis" wrote: > > Hello, have a Yak55 which just presented with an engine or prop surge, after doing moderate acro. Initial indication was a rapid loss in performance. After throttle back, settled down to a constant surge. Fuel pressure was good and constant,have checked the entire fuel system everything is clean and clear. Can`t duplicate the problem on the ground during runup. But did surge again on next test flight. Would like to know if the aneriod diaphragm or the larger pressure diaphragm were failing could cause this, although no garbage was found in the carb screens. Or should I focuse on the prop and governor. Governor screen is clean as well. Has anybody run across this situation? Thanks > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=399918#399918 > > > > > > > > > > ________________________________ Message 3 _____________________________________ Time: 06:21:01 PM PST US From: Javier Carrasco Subject: Re: Yak-List: yak 55 engine surge, in flight I used to have a similar issue but after prolonged discent at lw RPM settin gs. - After changing to the auto spark plugs an keeping the temps over 150. never had it again. - Good luck. - Javier Carrasco Yak-55m N5245H --- On Fri, 5/3/13, Epistaxis wrote: From: Epistaxis Subject: Yak-List: yak 55 engine surge, in flight Hello,- have a Yak55 which just presented with an engine or prop surge, a fter doing- moderate acro. Initial indication was a rapid loss in perform ance. After throttle back, settled down to a constant surge. Fuel pressure was good and constant,have checked the entire fuel system everything is cle an and clear. Can`t duplicate the problem on the ground during runup. But d id surge again on next test flight. Would like to know if the aneriod diaph ragm or the larger pressure diaphragm were failing could cause this, althou gh no garbage was found in the carb screens. Or should I focuse on the prop and governor. Governor screen is clean as well.- Has anybody run across this situation?- - ---Thanks Read this topic online here: http://forums.matronics.com/viewtopic.php?p=399918#399918 le, List Admin. ________________________________ Message 4 _____________________________________ Time: 06:45:41 PM PST US Subject: Yak-List: Re: yak 55 engine surge, in flight From: "Epistaxis" Doc, thanks for the response, could you please clarify where you found sections of the flapper valve, which filter IE...course or fine on the firewall or in the carb inlet course screen, and was this part of the emergency fuel shut off flap. In addition, this evening after returning to the hanger and after the test flight this afternoon have found fuel dripping from and around the spray bar in the carb venturi. Thanks Read this topic online here: http://forums.matronics.com/viewtopic.php?p=399929#399929 ________________________________ Message 5 _____________________________________ Time: 07:05:49 PM PST US From: Thomas Geoghegan Subject: Yak-List: Front Gear Level (CJ6) Today when I turned on my main air, I had a rush of air escaping near the front gear handle. Cycling between down & neutral didn't stop the leak, with the neutral position producing more hissing. Looking at the front of the selector assembly, there appears to be two holes (to the left of the selector & behind the gear slide lock) overtop each other. The air is escaping from the bottom hole. Can some one explain how this shifter assembly is constructed? Is it repairable or does the entire unit get replaced? Thanks, Tommy ________________________________ Message 6 _____________________________________ Time: 07:17:34 PM PST US Subject: Re: Yak-List: Re: yak 55 engine surge, in flight From: "Roger Kemp M.D." A 6 mm and a 4 mm fragment of the inner liner of the main fuel line to the carb. We found it in the finger screen in the carb. It is not uncommon to have a small amount of fuel drip out of the carb after shutdown especially if you do not advance the throttle to wide open just as you cut the mags off. I am by no means an expert on the carb. Doc Sent from my iPad On May 3, 2013, at 8:43 PM, "Epistaxis" wrote: > > Doc, thanks for the response, could you please clarify where you found sections of the flapper valve, which filter IE...course or fine on the firewall or in the carb inlet course screen, and was this part of the emergency fuel shut off flap. In addition, this evening after returning to the hanger and after the test flight this afternoon have found fuel dripping from and around the spray bar in the carb venturi. Thanks > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=399929#399929 > > > > > > > > > > ________________________________ Message 7 _____________________________________ Time: 07:33:05 PM PST US Subject: Re: Yak-List: Front Gear Level (CJ6) From: "Roger Kemp M.D." Put your a/c up on jacks for safety as if you are going to swing the gear to test them. Place the rear gear selector in the down position. Move the front cockpit selector to the neutral position with the air turned own. If the hissing in the front cockpit transfers to the rear cockpit selector then it is a check valve from one of the gear check valves that is leaking. If there is no RCP selector leakage then it is the FCP selector that is bad. That is the way it works in the YAK. Just finished changing the FCP gear selector on the 52. Sent from my iPad On May 3, 2013, at 9:03 PM, Thomas Geoghegan wrote: > > Today when I turned on my main air, I had a rush of air escaping near the front gear handle. Cycling between down & neutral didn't stop the leak, with the neutral position producing more hissing. > > Looking at the front of the selector assembly, there appears to be two holes (to the left of the selector & behind the gear slide lock) overtop each other. The air is escaping from the bottom hole. > > Can some one explain how this shifter assembly is constructed? Is it repairable or does the entire unit get replaced? > > Thanks, > Tommy > > > > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message yak-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/Yak-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/yak-list Browse Digests http://www.matronics.com/digest/yak-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.