Loss of pressurization Incident Avro RJ85 EX-27003, Wednesday 18 August 2021

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Date:	Wednesday 18 August 2021
Time:
Type:	Avro RJ85
Owner/operator:	Tez Jet
Registration:	EX-27003
MSN:	E2296
Engine model:	Lycoming LF507-1
Fatalities:	Fatalities: 0 / Occupants: 75
Other fatalities:	0
Aircraft damage:	None
Category:	Incident
Location:	near Osh - Kyrgyzstan
Phase:	En route
Nature:	Passenger - Scheduled
Departure airport:	Osh Airport (OSS/UCFO)
Destination airport:	Bishkek-Manas International Airport (FRU/UCFM)
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
TezJet flight TEZ128, an Avro RJ85, suffered a cabin presurization issued after departure from Osh. The aircraft returned to Osh.

Conclusion: Failure of the automatic boost control system along the exhaust valve No. 2 which was stuck open.
The air pressure control system in the passenger cabin could not maintain the set pressure as too much air flow went through the open exhaust valve No. 2.

Accident investigation: