An air ambulance helicopter crashed when one of the main rotor blades came apart in flight. The three-person crew was killed.
The rotor blades were made of composite materials that were almost entirely consumed in the post-crash fire. Government investigators worked for more than a year but, with little evidence available, never determined why the rotor blade failed.
We gathered and examined thousands of pages of documents related to the maintenance of the helicopter and the rotor blades. A seemingly insignificant document — a mechanic’s daily time record from years before the crash — recorded the fact that the mechanic had performed a routine procedure, removing a metal abrasion strip from the leading edge of one of the blades.
We noticed, however, that the mechanic had spent less time on this job than on other similar jobs. The strip was attached to the blade with adhesive and it was a slow and time-consuming task to remove the adhesive with a heat gun. We discovered that, to speed the process, the mechanic had used a blowtorch instead.
By experimenting with other rotor blades, we discovered that using a blowtorch would soften not just the glue attaching the metal strip but also the glue deep inside the blade and along its structural spar. The blade’s internal structure was compromised by the mechanic’s shortcut. The fatal crash was the eventual consequence.
The case was settled for $12 million.