SINGAPORE, May 29 (Reuters) - Preliminary findings from an investigation into a Singapore Airlines flight hit by severe turbulence last week showed a rapid change in gravitational force and 54 meter altitude drop caused injuries, Singapore's transport ministry said on Wednesday.

One passenger died of a suspected heart attack and dozens were injured after Singapore Airline Flight SQ321, flying from London to Singapore, encountered what the airline described as sudden, extreme turbulence while flying over Myanmar. The ministry said the investigation was ongoing. (Reporting by Martin Petty and Xinghui Kok; Editing by John Mair)