EMB145 flight crew during preflight has a failed #1 inverter indication. Failure of #1 AC inverter c...

Attributes
ACN	686610
Time
Date	200602
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ind.airport
State Reference	IN
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	EMB ERJ 145 ER&LR
Operating Under FAR Part	Part 121
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time total : 4000
ASRS Report	686610
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : less severe
Independent Detector	aircraft equipment : gpws aircraft equipment : tcas aircraft equipment other aircraft equipment : eicas warning other flight crewa other flight crewb other other : 3
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	Aircraft Company Flight Crew Human Performance Maintenance Human Performance
Primary Problem	Aircraft

Narrative:

We called maintenance to the aircraft because of '115 vac off bus' presented on the EICAS at power-up. Maintenance couldn't fix it and had no spare inverters; so the decision was made to defer it under MEL 'inverter.' the MEL states that the TCAS and GPWS should be considered inoperative since those system are on the AC bus. Nowhere does the MEL direct the crew to what that means operationally. In other words; we had to look up the TCAS and GPWS separately. After doing so; we determined that an inoperative TCAS was no problem but an inoperative GPWS stated that no takeoff or landing shall be attempted when there is a possibility for windshear at the field. Our destination was an airport on the bay where 'windshear advisories are in effect' is heard more times than not on the ATIS. Additionally the metar reported winds at 280 degrees; 15 KTS; gusting to 25 KTS -- an ideal environment for windshear. The coordinator backed me up and gave me another airplane resulting in a delay but no cancellation.

Original NASA ASRS Text

Title: EMB145 FLT CREW DURING PREFLT HAS A FAILED #1 INVERTER INDICATION. FAILURE OF #1 AC INVERTER CAUSES LOSS OF THE TCAS AND GPWS. MEL ALLOWS FOR THE FLT TO PROCEED WITH THE FAILURE. FLT CREW ELECTS TO NOT PROCEED INTO KNOWN WINDSHEAR CONDITIONS WITHOUT THE GPWS AND SWITCHES ACFT.

Narrative: WE CALLED MAINT TO THE ACFT BECAUSE OF '115 VAC OFF BUS' PRESENTED ON THE EICAS AT PWR-UP. MAINT COULDN'T FIX IT AND HAD NO SPARE INVERTERS; SO THE DECISION WAS MADE TO DEFER IT UNDER MEL 'INVERTER.' THE MEL STATES THAT THE TCAS AND GPWS SHOULD BE CONSIDERED INOP SINCE THOSE SYS ARE ON THE AC BUS. NOWHERE DOES THE MEL DIRECT THE CREW TO WHAT THAT MEANS OPERATIONALLY. IN OTHER WORDS; WE HAD TO LOOK UP THE TCAS AND GPWS SEPARATELY. AFTER DOING SO; WE DETERMINED THAT AN INOP TCAS WAS NO PROB BUT AN INOP GPWS STATED THAT NO TKOF OR LNDG SHALL BE ATTEMPTED WHEN THERE IS A POSSIBILITY FOR WINDSHEAR AT THE FIELD. OUR DEST WAS AN ARPT ON THE BAY WHERE 'WINDSHEAR ADVISORIES ARE IN EFFECT' IS HEARD MORE TIMES THAN NOT ON THE ATIS. ADDITIONALLY THE METAR RPTED WINDS AT 280 DEGS; 15 KTS; GUSTING TO 25 KTS -- AN IDEAL ENVIRONMENT FOR WINDSHEAR. THE COORDINATOR BACKED ME UP AND GAVE ME ANOTHER AIRPLANE RESULTING IN A DELAY BUT NO CANCELLATION.

Data retrieved from NASA's ASRS site as of January 2009 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.

EMB145 flight crew during preflight has a failed #1 inverter indication. Failure of #1 AC inverter causes loss of the TCAS and GPWS. MEL allows for the flight to proceed with the failure. Flight crew elects to not proceed into known windshear conditions without the GPWS and switches aircraft.