# NTSB Incident MIA99IA046
> **Boeing 737-232** · 1998-12-15 · ORLANDO, FL, USA · NONE
## Event
- **NTSB number:** MIA99IA046
- **Event ID:** 20001211X11596
- **Type:** Incident
- **Date:** 1998-12-15
- **Location:** ORLANDO, FL, USA
- **Coordinates:** 28.419565, -81.300033
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 56
- **Total aboard:** 56
## Aircraft
- **Make:** Boeing
- **Model:** 737-232
- **Registration:** N327DL
- **FAR Part:** 121
- **Engines:** 2
- **Damage:** MINR
## Conditions
- **Light:** DAYL
- **Weather:** VMC
## Probable cause

A discharged battery due to a loss of electrolyte, and the latent shorted failures of the No. 1 and 2 generator control unit (GCU) blocking diodes (CR910) for undetermined reasons. These failures resulted in an excessive current drawn from both GCUs, during the flight crew's attempt to start the auxiliary power unit, that caused the immediate overload (opening) of the AC power supply input fuses (POR fuses) internal to each GCU, and subsequent loss of the No.1 and 2 generators; complete discharge of the battery, and subsequent total loss of electrical power. Contributing to the incident was the incorrect reading of the cockpit DC voltmeter (read higher than actual reading) allowing the flight crew to depart with an unreliable (discharged) battery.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=MIA99IA046) · AI Analytics · CC0 1.0*