---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Tue 07/17/12: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:39 AM - pitot system leaks () 2. 08:09 AM - Re: pitot system leaks (Kevin Horton) 3. 08:51 AM - Re: pitot system leaks (Brian Alley) ________________________________ Message 1 _____________________________________ Time: 07:39:50 AM PST US From: Subject: RV-List: pitot system leaks The vertical velocity indicator needs to be clamped or blocked. That instrument has a =9Ccalibrated=9D leak in it. It=99s the difference between the calibrated leak and pressure coming from the static port as the plane ascends or descends that cause the needle to deflect. As the plane continues to ascend or descent there will continue to be a pressure differential. Once the plane levels off the static pressure becomes constant. The calibrated leak will then slowly match the static pressure and the needle will slowly return to zero. If there is no calibrated leak, the VSI would act like an altimeter... Joe Connell Stewartville, MN Time: 08:40:12 AM PST US Subject: Re: RV-List: pitot system leaks From: thomas sargent I am still getting no where in testing my static system (or the static system leaks horribly). Does the connection to the VSI have to be sealed off before testing? ________________________________ Message 2 _____________________________________ Time: 08:09:33 AM PST US Subject: Re: RV-List: pitot system leaks From: Kevin Horton The "calibrated leak" in the VSI is internal to the VSI. It is not a leak between the VSI and ambient pressure. The only way air can get into or out of a serviceable VSI is at the connection to the static system. There is no need to disconnect the VSI to do a static system leak check. I just had my system checked by an avionics shop a few weeks ago. It passed with zero leaks, without disconnecting anything. Kevin Horton On 2012-07-17, at 10:38 , wrote: > The vertical velocity indicator needs to be clamped or blocked. That instrument has a calibrated leak in it. Its the difference between the calibrated leak and pressure coming from the static port as the plane ascends or descends that cause the needle to deflect. As the plane continues to ascend or descent there will continue to be a pressure differential. Once the plane levels off the static pressure becomes constant. The calibrated leak will then slowly match the static pressure and the needle will slowly return to zero. If there is no calibrated leak, the VSI would act like an altimeter... > > Joe Connell > Stewartville, MN > > Time: 08:40:12 AM PST US > Subject: Re: RV-List: pitot system leaks > From: thomas sargent > > I am still getting no where in testing my static system (or the static > system leaks horribly). Does the connection to the VSI have to be sealed > off before testing? > ________________________________ Message 3 _____________________________________ Time: 08:51:48 AM PST US Subject: Re: RV-List: pitot system leaks From: Brian Alley Good point, static system instruments AI, Alt and VSI are closed systems. Otherwise they would not work in a pressurized aircraft. There should not be anything disconnect during calibration, but troubleshooting a problem is a different situation! Sent from my iPhone Brian Alley carbonfibercomposites.net 304-395-4932 On Jul 17, 2012, at 11:08 AM, Kevin Horton wrote: > > The "calibrated leak" in the VSI is internal to the VSI. It is not a leak between the VSI and ambient pressure. The only way air can get into or out of a serviceable VSI is at the connection to the static system. > > There is no need to disconnect the VSI to do a static system leak check. I just had my system checked by an avionics shop a few weeks ago. It passed with zero leaks, without disconnecting anything. > > Kevin Horton > > > > On 2012-07-17, at 10:38 , wrote: > >> The vertical velocity indicator needs to be clamped or blocked. That instrument has a calibrated leak in it. Its the difference between the calibrated leak and pressure coming from the static port as the plane ascends or descends that cause the needle to deflect. As the plane continues to ascend or descent there will continue to be a pressure differential. Once the plane levels off the static pressure becomes constant. The calibrated leak will then slowly match the static pressure and the needle will slowly return to zero. If there is no calibrated leak, the VSI would act like an altimeter... >> >> Joe Connell >> Stewartville, MN >> >> Time: 08:40:12 AM PST US >> Subject: Re: RV-List: pitot system leaks >> From: thomas sargent >> >> I am still getting no where in testing my static system (or the static >> system leaks horribly). Does the connection to the VSI have to be sealed >> off before testing? >> > > > > > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV-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/rv-list Browse Digests http://www.matronics.com/digest/rv-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.