FMEA VH-TBA SDS-EFI.xlsx

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1	RV-14 VH-TBA with SDS EFI - FMEA												Electrical Generation Rev 2
2	In Flight: Normal Switch Positions - ENG PRI/SEC MSTR - CLSD (ON), L/R BAT MSTR - CLSD(ON), X-TIE MSTR: OPEN (OFF), ALTN: ON, SBY GEN: ON								-Master Caution / Master Warning indications not included in "in-flight detection", but will accompany fault conditions
3	Left Side: L BATT / ALTN / MAIN BUS + SEC Feed to Engine Bus. \| Right Side: R BATT / MZ30 / ESS BUS + PRI Feed to Engine Bus.
4	SBY GEN in PRI mode is 14.6V (14.1 @ Eng Bus), and ALTN is 14.4v (13.9 at Eng Bus), so MZ30 is primary provider for Engine Bus.
5	X-TIE allows for MZ30 to power Main side, and for ALTN to power ESS Side in the event of a ALTN/Gen failure.
6	Risk	#	Item	Failure Mode	In-Flight Detection	Existing Controls	Liklihood	In-Flight Effect	Immediate System Loss	Severity	Pilot Action	Recovery State	Notes

7	Low	1	L Battery	BMS Shutdown Battery Failure Short: L BATT POS Short: L BATT MSTR to START Contactor `	-L BATT FAULT CAS -L BATT LOW Volts CAS	Known Battery (EarthX)	Occasional	-Loss of redundancy for Main Bus -Loss of capacator function of battery - alternator may be unstable.	NIL	No Loss - Action Required	To prevent ALTN instability and shutdown: -Isolate Battery: "L BATT" - OFF / "SEC BATT" - OFF ~> ALTN still powers the main bus side. Avoid changing loads on that bus. -Give ALTN access to R Battery: "BUS X-TIE" - OPEN ~> ALTN should operate as normal.	-Loss of ENG BUS FEED SEC -Loss of split bus fault protection
8	Low	2	R Battery	BMS Shutdown Battery Failure Short: R BATT POS Short: Feed to Engine Contactors	-R BATT FAULT CAS -R BATT LOW Volts CAS	Known Battery (EarthX)	Occasional	-Loss of redundancy on for Ess Bus / Eng Bus	NIL	No Loss	If isolation of battery is required: -Isolate Battery: "R BATT" - OFF / "PRI BATT" - OFF ~> ESS BUS will become depowered. Temoporary loss of single powered items (COM 1). All critical items are dual power fed. -Regain power: "BUS X-TIE" - CLSD (ON) ~>L BATT and ALTN can now power ESS BUS and any single powered items will be restored.	-No loss -Loss of split bus fault protection.
9	Low	3	"L BATT" Master Contactor "L BATT" Master Switch	Contactor Fail open Switch Fail open	Not Detectable unless ALTN instability or until shutdown	Common Use Contactor High Quality Switch	Improbable	-ALTN on Main Bus side will have no battery as a capacitor -May experience instability if loads applied	NIL	No Loss - Action Required	~> ALTN still powers the main bus side. Avoid changing loads on that bus. -Give ALTN access to R Battery: "BUS X-TIE" - OPEN ~> ALTN should operate as normal.	- No Loss
10	Low	4	"R BATT" Master contactor "R BATT" Master Switch	Contactor Fail open Switch Fail open	Items solely powered by ESS Bus would lose power (e.g. COM #1)	Common Use Contactor High Quality Switch	Improbable	-Items solely powered by ESS BUS (TBA) such as Com #1 would lose power, as both the battery and MZ30 are on the battery side of the R BATT contactor. ] -All critical or non-redundant avionics items are dual powered.	- Items which are not dual powered (COM #1) etc will be lost. - Loss of AP/TRIM/TAXI & LDG LTS / FLAPS / PITOT Heat	Non-Crit Sys Loss	-ESS can be re-powered by closing "X-TIE" switch	-No Loss once X-TIE is closed -MAIN ALTN is powering both MAIN and ESS busses	A consideration is to feed the essential bus via diodes. This can't be done via the engine bus feeds, or it defeats the concept of removing all power from the busses with the masters (smoke scenerio). Powering from the main bus achieves the same thing as using the X-TIE (which needs to be present for alternator power redundancy), so likely not worth it.
11	Low	5	"ENG SEC" Master Relay "SEC BATT" Switch "ENG BUS FEED SEC" Wire	Contactor Fail open Switch Fail open Short: ENG BUS FEED SEC	Not Detectable until next engine start via procedure	High Quality Relay & Switch	Improbable	- Loss of redundant power to ENG BUS from L BATT / Alternator - If short to "ENG BUS FEED SEC" the FLW will open	Nil	No Loss	Nil - Undetectable until next engine start	Loss of redundant feed to ENG bus.	Procedure: On start turn on one ENG battery switch one at a time and observe engine bus volts and fuel pump sound.
12	Low	6	"ENG PRI" Master Relay "PRI BATT" Switch	Contactor Fail open Switch Fail open	Not Detectable until next engine start via procedure	High Quality Relay & Switch	Improbable	-Loss of R BATT feed to ENG BUS (MZ30 Feed still present on PRI FEED line).	Nil	No Loss	Nil - Undetectable until next engine start	Loss of R BATT fedd to ENG BUS	Procedure: On start turn on one ENG battery switch one at a time and observe engine bus volts and fuel pump sound.
13	Low	7	"ENG BUS FEED PRI" Wire	Short	ENG BUS volts would drop from 14.1 to 13.9 (ALTN)	Robust Wire Runs	Very Improbable	-FLW would open on wire -No power could feed engine bus from R BATT or MZ30.	Nil	No Loss	- Nil Action required. MAIN ALTN and L BATT would continue to power ENG BUS - BUS protected from short by diodes on feeds input.	-Loss of redundant feed on Eng BUS -If ALTN also faile, "Bus X-TIE" could be used to feed main bus side / Eng bus side though "ENG BUS FEED SEC"	Set ENG BUS volts waring to 14.0v?
14	Low	8	MZ30 Generator "SBY GEN SRC" Wire	Generator or Regulator Fail Short: "SBY GEN SRC"	-ENG BUS drops from 14.1 to 13.9v (ALTN) -Possible "SBY GEN FAULT" CAS	Quality Product Blast Cooling of Regulator / Generator Robust Wire Runs	Occasional	-ENG BUS would be fed by the ALTN through the L Batt Master and the SEC BAT engine master relay, and would be higher volts than the R battery. -ESS BUS would be feeding off the R Battery only (most items on ESS BUS would be dual fed from higher Voltage MAIN BUS, so draw from battery would be low).	Nil	No Loss	-If R BATT draw is unaccepatble from ESS BUS, then 'BUS X-TIE' may be utilised to both charge the R BATT, as well as power the ESS BUS.	-If X-TIE Used: Loss of independent busses.
15	Low	9	MAIN ALTN "PRI ALTN B-LEAD" Wire VOLTAGE Regulator	-ALTN Fail -ALTN Shutdown (Short, Overvolts) -Short: "PRI ALTN B-LEAD" - Regulator Fail	-L Battery Low Volts -"MAIN ALTN LOW VOLTS" CAS	-B&C Alternator known for reliability -Robust Wire Runs	Improbable	-MAIN BUS would be powered solely by L BATT -Load would be picked up on dual fed items from ESS BUS -single powered non-essential items would draw down battery. -ENG BUS would be fed by MZ30	Nil	No Loss	-If rate of discharge of L BATT was too high, 'BUS X-TIE' could be closed to allow MZ30 to charge L BATT, as well as power MAIN BUS.	-If X-TIE Used: Loss of independent busses.
16	Low	10	"ESS BUS FEED" Wire	-Short -Opening of Fusible Link	- Loss of single power items on ESS Bus (COM #1 etc) - ESS BUS AMPS drops to zero	- Fusible link opens to prevent fire etc. - Robust wire Runs	Very Improbable	- Loss of ESS BUS power.	- Items which are not dual powered (COM #1) etc will be lost. - Loss of AP/TRIM/TAXI & LDG LTS / FLAPS / PITOT Heat	Non-Crit Sys Loss	Nil Pilot action can be taken		Consider if backup power to any of the ESS bus items is feasible. (flaps / AP / Trim?). This would guard against loss of the ESS bus via a shorted wire only. There are spare spots on the diodes. Only guards against shorted wire (see #4 above)
17	Low	11	"MAIN BUS FEED" Wire	-Short -Opening of 100a MIDI	-loss of single power items on MAIN bus -MAIN BUS AMPS drops to zero	-MIDI opens to prevent fire -Robust wire runs	Very Improbable	-Loss of MAIN BUS power	-Items which are not dual powered (COM #2) etc will be lost -Position Lts / Cockput Lights / MAP lt / Smoke system (all non-critical)	Non-Crit Sys Loss	Nil Pilot action can be taken
18	Low	12	"L BATT HOT" Wire "R BATT HOT" Wire	-Short -Opening of Fusible Link	-L BATT or R BATT volts drop to zero	-Fusible Link opens to prevent fire -L BATT: Loss of any hot battery items (if this bus ends up making it into production)	Very Improbable	-Loss of Battery Volts indications	-Nil	No Loss	Nil Pilot action can be taken
19	Low	13	X-TIE Master	Contactor Fail Open	Not Detectable	Quality Product	Very Improbable	- Loss of cross-tie ability in the event of multiple failures	-Nil	No Loss	Nil Pilot action can be taken		Check of operation can be done monthly (refer "Startup Switching")
20	Low	-	Smoke Present in the Cockpit	Unknown Wire Short	Smoke Present	Robust Wire Runs	Very Improbable	- Refer to above wire short scenerios	- Refer to above wire short scenerios	Non-Crit Sys Loss	-MASTERS: "L BATT", "ALTN", "R BATT" all off. - All avionics power down, except for G5 which is powered by the ENG BUS	- No IFR approach capability unless systems recovered. - with MAIN BUS unpowered, items which are not dual powered (COM #2) etc will be lost -Position Lts / Cockput Lights / MAP lt / Smoke system (all non-critical)	- Systems can be restored by pulling all ESS BUS Cb's. - Power to ESS BUSS can be restored by turning the "R BATT" master back on. - One by One the CB's can be restored. GAD27 PWR restores PFD, EIS(GEA24) and Mag HDG(GMU11) via KEEP ALIVE power
21	Low	14	ENG PRI / SEC Diodes	Failure Open	Not Detectable	-Plan to mount on heatsink (thick ALU plate) -Rated at 120A and 150C & 14v RRM, so diodes should not be working too hard.	Occasional	- Loss of redundant power to ENG BUS from it's associated BATT.	-Nil	No Loss	Nil Pilot action can be taken		-A diode check is conducted weekly - where ENG BUS volts / Fuel Pump sound is monitored using both the PRI BATT and SEC BATT switches - chekcing both diodes are serviceable.
22	Low	14	ENG PRI / SEC Diodes	Failure SHORT	Not Detectable	-Plan to mount on heatsink (thick ALU plate) -Rated at 120A and 150C & 14v RRM, so diodes should not be working too hard.	Occasional	- Loss of split bus functionality / protection - Current could flow through diode in both directions	-Nil	No Loss	Nil Pilot action can be taken		Maintenance Function at 100hrly to check voltage on diode - R BATT ON (only) / Check volts is 0 on input side of ENG SEC Diode - L BATT ON (only) / Check volts is 0 on input side of ENG PRI Diode
23	Low	15	ENG BUSS	Short on ENG BUS itself	Engine Stoppage!	- Good Quality Product - Buss-Bar on the back is covered with "liquid electrical tape" - Fuse Block is angled at 45 degrees down, reducing liklihood of something falling onto it and shorting to ground.	Very Improbable	- Engine Stoppage - One or Both Fusible links on PRI/SEC feeds may open	- Engine Stoppage	Engine Stop	Land in a paddock!
24	Low	16	ESS BUSS	Short on ESS BUS itself	- Loss of single power items on ESS Bus (COM #1 etc) - ESS BUS AMPS drops to zero	-Copper Bar / CB's design used on many aircraft over many years - Where possible, heat shrink is used on copper bars - Bus is angled at 45 degrees down, reducing liklihood of something falling onto it and shorting to ground.	Very Improbable	- Loss of ESS BUS power.	- Items which are not dual powered (COM #1) etc will be lost. - Loss of AP/TRIM/TAXI & LDG LTS / FLAPS / PITOT Heat	Non-Crit Sys Loss	Nil Pilot action can be taken
25	Low	17	MAIN BUSS	Short on MAIN BUSS itself	-loss of single power items on MAIN bus -MAIN BUS AMPS drops to zero	- Good Quality Product - Buss-Bar on the back is covered with "liquid electrical tape" - Fuse Block is sub panel mounted, so the back is in-accessible.	Very Improbable	- Loss of MAIN BUSS power	-Items which are not dual powered (COM #2) etc will be lost -Position Lts / Cockput Lights / MAP lt / Smoke system (all non-critical)	Non-Crit Sys Loss	Nil Pilot action can be taken
26	Low	18	Ground Stud on FWF Forrest of Tabs L BATT -NEG R BATT - NEG	Nut comes loose on Ground Bolt	- L or R BATT Volts drop to zero	- Known good quality B&C Unit - Lock Washer	Improbable	- Losing all grounds back to the batteries may cause loss of bus power. -Alternators should continue to have ground, but main alternator may be erratic (loss of capacitance function).	- Unknown but possible system loss	IFR B/UP Inst			-Consider utilising two firewall forward forrest of tabs with each battery coming back to it's own ground. Both ground studs should be linked using 35mm welding cable so the gounds are linked. This would enable a L and a R forrest of tabs, which might make wiring the grounds easier.
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53	Notes / Action Items
54		1	Consider some on ground checks (perhaps at 50 hourly) to check X-TIE is fucntioning. L BATT on (only L screen starts up), X-TIE on (both screens start up) etc.
55		2	If the TOTAL LOAD is above 30A, then since the X-TIE is open, BOTH batteries would deplete slowly. The main power users are PITOT HEAT (and FLAPS) but these can be turned off / not used etc. Need to do a worst case load analysis to see if a MAIN BUS shed relay is needed. If the X-TIE is left OPEN, then the R BATT only would deplete. Better to have this as an alternate source for the engine bus, and shed the main bus if need be. PITOT should remain in ESS BUS as this may be needed for IFR flight. FLAPS can stay on MAIN BUS as these are non-critical.
56		3	SBY gen should be checked at pre-flight, by turning off MAIN ALTN. Sby should kick in with "MAIN ALT LOW VOLTS" and "SBY GEN ON". Bus volts should change from 14.4 volts on MAIN ALTN, to 14.2 volts in SBY GEN. If lower than this, then the MZ30 is not working.
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