Narrative:

Approximately 2+20 after departure; IFR; on route segment direct for GPS approach. At FL190; performed descent check; requested descent; and 30 seconds after beginning descent at required 1300-1400 FPM from FL190 to cleared altitude of 15;000; autopilot disengaged with warning tone; then alternator 1; alternator 2; low voltage warning lights and main/essential voltage warning indicators became visible on pfd. In addition to loss of autopilot; noted loss of pitch and roll aircraft trim; in addition to electrical warnings. Thus; continued descent without aircraft trim while troubleshooting and determining severity of situation (loss of all aircraft electrical generation while IMC). Immediately referred to paper checklist for circuit breaker identification and referred to mfd for electronic checklist for low voltage & loss of alternator(s) procedures. Due to flight conditions; this failure deemed critical due to operation of all aircraft comm/nav equipment on battery power only! Flight conditions at time; tops to over FL190; with layers and scattered to broken cumulus coverage between FL190 and approx 6000 to 7000 feet; with solid IMC conditions expected between 6000 and local ceilings. Local ceiling reported between 500-600 ft west of position to approx 900-1500 ft east of position (ATIS reported 1300 ovc). Based near 100% chance of requiring IMC descent on battery power; immediately shed non-essential switched equipment (lights; pitot heat) then executed alternator reset procedure for alternator #1; cycled switch off; reset breaker (also noted both alternator #1 and #2 breakers popped); switched alternator #1 on; immediately popped alternator #1 breaker. Left alternator #1 off and breaker out; applied checklist procedure for #2; (switch off; reset breaker; switch on; immediately popped alternator #2 breaker). At this point; with intermittent IMC; noted altitude approaching 14;300 feet; immediately reversed descent to climb; while simultaneously reporting deviation and declaring emergency to center and returning to 15;000 ft -- total time of deviation below 15;000; less than 15 seconds. When level at 15;000; coordinated for immediate descent under emergency conditions; requested shortest route (vectors to GPS approach) briefing controller that we'd need to penetrate the weather on battery power only and time was of the essence. Controller granted immediate (incremental descent to lower (recall 11;000) and coordinated hand off to approach. During descent continued methodical elimination of electrical loads via reference to paper checklist to drop 30 amps to approx 7-8 amps. Due to severity; made second attempt to execute alt#1 and alternator #2 reset procedures by checklist with same results; admitted battery power was only option remaining -- extensive cockpit reconfiguration required to eliminate loads but retain IFR comm/nav capabilities; eventually shed all but pfd; mfd; comm/navigation/GPS #1; transponder; backup instruments and other essential items. Of special note; backup battery powered (handheld) GPS navigation system with approach plates was in use by pilot as a precaution due to low ceilings and visibility for intended flight. This was available throughout the flight and continued to operate in addition to pfd; mfd (with approach plates) and printed approach chart for bases on route of flight. On hand over to approach; immediately checked in with emergency status; request vectors to GPS X to shorten flight time; then requested immediate descent; cleared to (incrementally to) 4000 ft; then requested confirmation and clearance to minimum vectoring altitude (2000'). Cleared to MVA of 2000; at 2000 ft; intermittent ground contract; but only about 15% of time; not adequate for visual flight. Flew vectors and intercepted the GPS final approach course at 2000 ft and near cruise airspeed; due to lack of aircraft trim (aircraft trimmed for cruise speed); plus higher airspeed minimized ETA to final approach. After GPS waas lpv glideslope intercept; descended on glideslope; breaking out between 800 and 1100 ft AGL; acquired runway at approx 2.5 miles visually; slowed aircraft to flap speed; used 50%; then full flaps with landing assured. Subsequent normal touchdown and rollout; despite lack of aircraft trim. Escorted to parking by crash rescue; met by FBO mechanics and fire chief elected to open cowling to visually inspect aircraft wiring in presence of fire team to ensure no fire potential remained. Confirmed no visible damage; nor presence of fire hazard; completed info form for fire chief; then began coordination with FBO for possible maintenance support. Subsequently contacted cirrus service center; reported malfunctions and severity. Raised concern about loss of both alternators being extremely serious and fact that this malfunction was purported to be 'not possible' due to isolation of electrical buses and systems. Cirrus pledged support; and agreed malfunction was 'atypical' and that the system was designed to prevent such dual alternator failures. Maintenance reported runaway voltage on alternator #1; still troubleshooting reason for dual failure. Also trouble shooting any relationship to other aircraft systems.

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Original NASA ASRS Text

Title: SR22 pilot reports dual alternator failure at FL190 and descent and landing in IMC with battery power only.

Narrative: Approximately 2+20 after departure; IFR; on route segment direct for GPS approach. At FL190; performed descent check; requested descent; and 30 seconds after beginning descent at required 1300-1400 FPM from FL190 to cleared altitude of 15;000; autopilot disengaged with warning tone; then alternator 1; alternator 2; low voltage warning lights and main/essential voltage warning indicators became visible on PFD. In addition to loss of autopilot; noted loss of pitch and roll aircraft trim; in addition to electrical warnings. Thus; continued descent without aircraft trim while troubleshooting and determining severity of situation (loss of all aircraft electrical generation while IMC). Immediately referred to paper checklist for circuit breaker ID and referred to MFD for electronic checklist for low voltage & loss of alternator(s) procedures. Due to flight conditions; this failure deemed critical due to operation of all aircraft comm/nav equipment on battery power only! Flight conditions at time; tops to over FL190; with layers and scattered to broken cumulus coverage between FL190 and approx 6000 to 7000 feet; with solid IMC conditions expected between 6000 and local ceilings. Local ceiling reported between 500-600 FT west of position to approx 900-1500 FT east of position (ATIS reported 1300 OVC). Based near 100% chance of requiring IMC descent on battery power; immediately shed non-essential switched equipment (lights; pitot heat) then executed alternator reset procedure for alternator #1; cycled switch off; reset breaker (Also noted BOTH alternator #1 and #2 breakers popped); switched alternator #1 on; immediately popped alternator #1 breaker. Left alternator #1 off and breaker out; applied checklist procedure for #2; (switch off; reset breaker; switch on; immediately popped alternator #2 breaker). At this point; with intermittent IMC; noted altitude approaching 14;300 feet; immediately reversed descent to climb; while simultaneously reporting deviation and declaring emergency to Center and returning to 15;000 FT -- total time of deviation below 15;000; less than 15 seconds. When level at 15;000; coordinated for immediate descent under emergency conditions; requested shortest route (vectors to GPS approach) briefing Controller that we'd need to penetrate the weather on battery power only and time was of the essence. Controller granted immediate (incremental descent to lower (recall 11;000) and coordinated hand off to approach. During descent continued methodical elimination of electrical loads via reference to paper checklist to drop 30 amps to approx 7-8 amps. Due to severity; made second attempt to execute alt#1 and alternator #2 reset procedures by checklist with same results; admitted battery power was only option remaining -- extensive cockpit reconfiguration required to eliminate loads but retain IFR comm/nav capabilities; eventually shed all but PFD; MFD; COMM/NAV/GPS #1; transponder; backup instruments and other essential items. Of special note; backup battery powered (handheld) GPS navigation system with approach plates was in use by pilot as a precaution due to low ceilings and visibility for intended flight. This was available throughout the flight and continued to operate in addition to PFD; MFD (with approach plates) and printed approach chart for bases on route of flight. On hand over to Approach; immediately checked in with emergency status; request vectors to GPS X to shorten flight time; then requested immediate descent; cleared to (incrementally to) 4000 FT; then requested confirmation and clearance to minimum vectoring altitude (2000'). Cleared to MVA of 2000; at 2000 FT; intermittent ground contract; but only about 15% of time; not adequate for visual flight. Flew vectors and intercepted the GPS final approach course at 2000 FT and near cruise airspeed; due to lack of aircraft trim (aircraft trimmed for cruise speed); plus higher airspeed minimized ETA to final approach. After GPS WAAS LPV glideslope intercept; descended on glideslope; breaking out between 800 and 1100 FT AGL; acquired runway at approx 2.5 miles visually; slowed aircraft to flap speed; used 50%; then full flaps with landing assured. Subsequent normal touchdown and rollout; despite lack of aircraft trim. Escorted to parking by crash rescue; met by FBO mechanics and Fire Chief elected to open cowling to visually inspect aircraft wiring in presence of fire team to ensure no fire potential remained. Confirmed no visible damage; nor presence of fire hazard; completed info form for fire chief; then began coordination with FBO for possible maintenance support. Subsequently contacted Cirrus Service Center; reported malfunctions and severity. Raised concern about loss of both alternators being extremely serious and fact that this malfunction was purported to be 'not possible' due to isolation of electrical buses and systems. Cirrus pledged support; and agreed malfunction was 'atypical' and that the system was designed to prevent such dual alternator failures. Maintenance reported runaway voltage on alternator #1; still troubleshooting reason for dual failure. Also trouble shooting any relationship to other aircraft systems.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.