New Delhi, Oct. 23 -- When Air India Flight 117's emergency power system deployed unexpectedly during a landing in Birmingham on October 4, it was part of a pattern affecting dozens of the aircraft - a Boeing 787-8 - worldwide, the aviation regulator has learnt.

As the Boeing Dreamliner jet approached the runway for landing, its emergency power turbine - the RAT, or ram air turbine - unexpectedly folded out of its fuselage when the jet was at 1,600 feet.

According to people aware of the matter, who asked not to be named, Boeing has told India's aviation regulator that 31 similar incidents have occurred globally on 787 aircraft. Nearly all - 29 cases - involved planes without a modified component that prevents the malfunction.

The RAT i...