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nuckolls.bob(at)aeroelect
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 Posted: Thu Jan 23, 2020 8:07 am Post subject: Is an ATC/ATO Fuse Block a Realistic Single Pt. of Failure |
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At 09:06 PM 1/22/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: "johnbright" <john_s_bright(at)yahoo.com>
Hi Mark,
In case this works for you... add a 2nd feed stud to the Bussman fuse block... https://photos.app.goo.gl/ZKjbqnU3DfkUKNex2
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Be circumspect about redundant feed paths to critical
loads . . . how will you know that one of htem is
not intact? The value of a dual feed path is
lost if integrity of each is not at least
pre-flight detectable or annunciated in
flight.
Bob . . .
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johnbright
Joined: 14 Dec 2011
Posts: 166
Location: Newport News, VA
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| Posted: Thu Jan 23, 2020 12:33 pm Post subject: Re: Is an ATC/ATO Fuse Block a Realistic Single Pt. of Fai |
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Thanks Bob,
I do understand, as importantly shown in the N811HB accident investigation, that failures that have no effect on the current flight should be detected before the next flight! Those unfamiliar with N811HB may well learn more than one lesson at http://www.aeroelectric.com/Reference_Docs/Accidents/N811HB_Feb2008_LA-IVp/
I am planning an O-360 with dual SDS ignition and injection. Part of my approach is to develop a detailed schematic of what it takes to keep the engine running, have a radio, and have a "six pack" of instruments long enough to make an alternate airport with the main contactors open (Z-14 derivative). I plan an engine bus with dual feeds, one from each battery via Schottky diodes; loss of either feed is preflight detectable using EFIS voltmeters.
I do a wire by wire failure analysis that informs the preflight checklist:
Assume only one failure per flight.
What are the effects of a wire shorted or open?
Does the failure affect safety? If so, can the safety effect be designed out?
How will the failure be discovered before the next flight?
If the failure affects flight safety, can something be done about it?
How will the crew know what to do? Can they do it immediately by simple predetermined actions?
In case of electrical fire can the battery contactor(s) be opened without affecting flight safety?
Some failures not detectable by preflight checks are added to annual inspection:
A fat wire short to sheetmetal that clears itself.
Redundant grounds for both the computer and the injector driver sections of the ECUs. (Loss of computer ground sends injectors and coils 100% duty cycle.)
Redundant grounds to voltage regulators.
Some check done twice yearly:
Ship's batteries and EFIS backup batteries capacity checks.
Primary and aux alternator crowbar test.
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_________________
John Bright, RV-6A, at FWF, O-360
Z-101 single batt dual alt SDS EM-5-F.
john_s_bright@yahoo.com, Newport News, Va
N1921R links |
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