Occurrence Summary
On 6 August 2009, a Boeing 757-200, registered G-LSAC, operated by Jet2, was on a scheduled roundtrip flight from Manchester (EGCC) to Tel Aviv (LLBG) and back. During the return leg, while cruising at FL360 in Romanian airspace at approximately 18:50, the pressure regulating shut-off valve of the right-hand (RH) engine bleed system failed. This led to a rapid increase in cabin altitude, triggering an emergency descent and diversion to Budapest Liszt Ferenc International Airport (LHBP). No injuries were reported, and the aircraft sustained no damage.
Sequence of Events
Prior to the incident, the aircraft's APU bleed system was inoperative, limiting the ability to provide outside air for cabin conditioning. During climb from Tel Aviv, a disparity between left-hand and right-hand pack duct pressures was noted, and the RH pack occasionally cycled to high flow. At approximately 18:30, the crew received RH PACK OFF and RH ENG BLEED messages, which reset automatically, then reappeared. The captain manually reset the RH engine bleed, clearing the messages. Passengers reported pressure fluctuations.
The RH pack and engine bleed failed again, and the captain switched them off. The left-hand pack failed to switch to high flow. The crew requested descent to FL340, where the cabin altitude continued climbing at 300 feet per minute, prompting further descent to FL280, where cabin altitude stabilized at 9,000 feet. Increasing speed to maintain bleed pressure led to higher fuel burn, so speed was reduced, causing cabin altitude fluctuations to resume.
A manual reset of the LH recirculation fan failed; the LH pack remained in low flow. A whooshing sound followed, and cabin altitude began climbing at 1,500 feet per minute. The crew initiated an immediate descent, donned oxygen masks, and released passenger oxygen masks. A MAYDAY was declared. The aircraft leveled at FL110, and the outflow valve remained closed throughout. The crew diverted to Budapest.
Passenger Medical Incident
A passenger with a history of angina complained of shortness of breath. A doctor on board attended to the passenger. Ground emergency and medical services were notified. After landing, the aircraft stopped on the taxiway to allow the passenger to deplane, then taxied to the stand under its own power.
Investigation and Follow-Up
The Transportation Safety Bureau (TSB) of Hungary led the investigation, with assistance from the UK's AAIB. The Cockpit Voice Recorder and Flight Data Recorder were read out. The operator revised the safety demonstration announcement within weeks of the incident and implemented changes to their procedures in January 2013. The TSB suggested issuing a safety recommendation to ICAO regarding cabin safety demonstrations.