Serious incident Boeing 777-32WER PT-MUG, Thursday 20 December 2018
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Date:Thursday 20 December 2018
Time:01:43 LT
Type:Silhouette image of generic B77W model; specific model in this crash may look slightly different    
Boeing 777-32WER
Owner/operator:LATAM Brasil
Registration: PT-MUG
MSN: 38888/1052
Year of manufacture:2012
Fatalities:Fatalities: 0 / Occupants: 355
Other fatalities:0
Aircraft damage: Minor
Category:Serious incident
Location:Belo Horizonte-Tancredo Neves International Airport, MG (CNF) -   Brazil
Phase: En route
Nature:Passenger - Scheduled
Departure airport:São Paulo-Guarulhos International Airport, SP (GRU/SBGR)
Destination airport:London-Heathrow Airport (LHR/EGLL)
Investigating agency: CENIPA
Confidence Rating: Accident investigation report completed and information captured
LATAM Airlines Brasil flight LA8084, a Boeing 777-300ER, diverted to Belo Horizonte, Brazil due to electrical problems.
The aircraft departed São Paulo-Guarulhos Airport at 00:27 hours local time (02:27 hours UTC) on a flight to London-Heathrow Airport, U.K.
At 00:42 hours, three fault messages related to the Electrical Backup System occurred. The messages were displayed to the crew members as "ELEC BACKUP SYS".
The crew then performed the "ELEC BACKUP SYS" checklist procedures. Due to these actions, two other failure messages were generated. At 00:50 hours, the flight leveled off at FL290.
Three minutes later there was a failure of the Main and Backup Electrical System, causing the de-energization of several aircraft functions.
The pilots lost both Primary Flight Displays (PFD), the two Navigation Displays (ND)s, the two EICAS and the two Electronic Flight Bags (EFBs). Additionally the automatic pilot was disconnected and the flight director and autothrottle functions were lost.
After a few seconds, the PFD and ND were restored, followed by the EICAS 30 seconds later.
The crewmembers activated the APU and, at 00:56, declared an emergency and elected to divert to Belo Horizonte.
An overweight landing was carried out at 01:43 hours. This caused all 12 tires of the main landing gear to deflate. The aircraft became disabled on runway 16, forcing the closure of the airport.

Contributing factors.
The deconfiguration of the Transfer Bus Breaker (TBB) and Converter Circuit Breaker (CCB), regardless of whether it was caused by the failures in the monitoring circuit of the contactors' position or due to a combination of these with previous failures of the oil level monitoring circuit, made the Main and Backup Electrical Systems unable to power the aircraft, even with power generation.
Even though it was not possible to determine how the short-circuit started in the connector or even to indicate the dynamics of the CCB and TBB deconfiguration, it is a fact that the failure generated a series of as-designed system reconfigurations, preventing the supply of the Main Electrical Systems and Backup, despite the generation of energy.
The loss of the Main and Backup System, due to the occurrence of a short-circuit in a connector and its splits, causing a deconfiguration of the TBB and CCB contactors, to the point of having their risk assessed as Class II, Hazardous, based on the exposure to the next critical fault, which would be the loss of RAT, could indicate a weakness in the aircraft's electrical system design.

Accident investigation:
Investigating agency: CENIPA
Report number: 
Status: Investigation completed
Duration: 2 years and 7 months
Download report: Final report


History of this aircraft

Other occurrences involving this aircraft

9 July 2024 PT-MUG LATAM 0 Milan-Malpensa Airport (MXP) unk



Revision history:

20-Dec-2018 11:26 NaamanHeckert Added
20-Dec-2018 11:33 harro Updated [Aircraft type, Registration, Cn, Operator, Location, Departure airport, Source, Embed code, Narrative]
20-Dec-2018 11:35 harro Updated [Time, Embed code, Narrative]
20-Dec-2018 12:02 harro Updated [Embed code, Narrative, Photo]
20-Dec-2018 13:41 Anon. Updated [Location, Embed code]
21-Dec-2018 06:55 Anon. Updated [Narrative]
23-Jul-2021 18:25 harro Updated [Total occupants, Destination airport, Source, Embed code, Narrative, Accident report]
09-Jul-2024 14:30 ASN Updated

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