---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 10/03/21: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 03:19 AM - Re: Estimates of Component Failure Probabilities (Peter Pengilly) ________________________________ Message 1 _____________________________________ Time: 03:19:12 AM PST US From: "Peter Pengilly" Subject: RE: AeroElectric-List: Estimates of Component Failure Probabilities There isn't much evidence based information available. My observation is electromechanical devices often fail during use/in flight due to vibration, solid state devices fail at start up. Vibration related failures are difficult to quantify because very few experimental owners have any kind of objective measure of the level of vibration (frequency vs amplitude) their equipment is exposed to. Those who have their engines dynamically balanced may have relatively low levels of vibration (0.2 ips at engine speeds & harmonics?) but how many do that? The only items I have any experience of failure rates are, Switches / relays - I've never had a failure in 2000 hours Alternators - 1 failure in 10x3 hours or less (not B&C) Magnetos - AvWeb did a survey some time ago, failure rate was 1 in 500 hrs. P-Mags - Better than magnetos by a factor of 2 to 5 (possibly more going forwards) SDS & Surefly - too early in their lifetime to really know, probably better than magnetos! Fuel systems - all pretty reliable, failures are often gradual. Lyc mech pumps have 2 diaphragms so will work with 1 ruptured. Isn't a Facet pump a traditional pump? Traditional fuel selectors leak all the time, Andair (my favourite) and SPRL are much better. Sensors do fail from time to time, if the system is well engineered the failure of any one sensor will not take the whole system down and is just an annoyance. Modern avionics very rarely fail and any failures are often due to installation errors, particularly in Experimentals. Although you didn't ask, vacuum systems have a failure rate of 1 in 500 hrs (AvWeb survey again), pretty much any EFIS will better that by a factor of 2 to 5 (data is about 8 years old). Installing a back-up attitude indicator with a battery (G5, AV-30, Horis, etc) will bring loss of attitude information into the 1 in 10^6 hours realm. Smart electrical systems (VPX, Expbus, etc) seem to be about as reliable as alternators in service. Hope this helps, but there just isn't much hard data available. Peter -----Original Message----- From: owner-aeroelectric-list-server@matronics.com On Behalf Of wsimpso1 Sent: 02 October 2021 14:27 Subject: AeroElectric-List: Estimates of Component Failure Probabilities --> I and another EAA chapter member are working on architecture decisions in our respective airplanes. In the process, I have assembled Failure Modes and Effects Analyses for several common options. Unfortunately, we have too small an experience base for confidence in estimating failure probabilities on the many components. We are looking for a broader experience set in estimating a number of things: Likelihood of Failure How likely individual items are to fail at engine start as opposed to in-flight? Will we be able to detect the failures using common post-start and pre-takeoff checklist processes? How likely are detection measures in finding impending failures? If an item is available from B&C, please assume they are the source. My colleague in this exercise is using a Lycoming with factory supplied Surefly Ignition and Bendix Fuel Injection. My homebuilt is planned with SDS fuel injection and ignition. Estimates specific to the hardware are great. Please help by giving your estimates of in-flight failure probabilities and any other thoughts you might have on detection and failure modes on the following components: Electrical components: Batteries; Carling DPDT switches; Continuous Duty Contactors; Continuous Duty Relays; Alternators; Regulators; Diode packs and Diodes; Ignition Equipment; Conventional Magnetos; E-Mags; SDS Ignition and Coils; Sure Fly Ignition; Fuel Handling; Mechanical Fuel Pumps; Electric Fuel Pumps, Traditional; Electric Fuel Transfer Pumps, Facet; Electric Fuel Injection Pumps, Walbro; SDS Fuel Injection; Fuel Selector Valves, Traditional; Fuel Selector Valves, Andair and Newton/SPRL Sensors supporting electronic fuel and spark; Avionics; Avidyne GPS/NAV/COM; Dynon HDX Display/Processors; Thanks in advance for any help you can give in these estimations. Billski Read this topic online here: http://forums.matronics.com/viewtopic.php?p=503375#503375 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-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/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-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.