A combination of maintenance gaps, a broken emergency stop mechanism and the actions of an inexperienced crew member were to blame for the catastrophic engine failure aboard scallop dragger Atlantic Destiny last year, a Transportation Safety Board investigation has found.

On March 14, Atlantic Destiny lost main engine power about 370 kilometres south of Yarmmouth, N.S. Thirty-one people were on board the factory freezer trawler, which is based in Riverport, N.S. Atlantic Destiny is part of the fleet owned by Ocean Choice International of Newfoundland and Labrador.

Clearwater scallop trawler Atlantic Preserver came to the 43-metre vessel's aid and towed it to Shelburne. No one was injured.

In its report released Monday, the TSB said there were "multiple unexpected engine shutdowns" aboard the ship in the years leading up to the March 14 incident.

As they had done in the past, the crew attempted to restart the engine while bypassing the governor — a speed-control system used to maintain the vessel's speed regardless of sea conditions.

According to the TSB report, while the ship's engineer was in the control room resetting the system, a deckhand — whom the TSB said had no experience or training in the engine room but was assisting the engineer — accidently set the fuel injection to 80 per cent instead of zero per cent.

Once the engine restarted, the crew was unable to reduce the speed because the engine controls were disabled at the time.

Adding to problems were the ship's speed sensors, which according to the TSB were either installed incorrectly or functioning only intermittently due to shorts in the electrical system. The TSB also said the engine emergency stop mechanism was broken, which caused the gearbox fluid couplings to fail in "an instantaneous overstress rupture due to excessive rotational speed," according to the report.

(After the incident, Ocean Choice International installed shielding around the engine's fluid couplings and replaced the aluminum floor plates above the fluid couplings with stronger ones.)

The TSB also found the company did not ensure crews were regularly testing the engine safety systems.

"If engine safety systems are not periodically tested in accordance with manufacturers' recommended schedules and repaired accordingly, there is a risk that engine safety systems will not operate as intended when a malfunction occurs," reads the report.

"As well, if untrained personnel are placed in an unfamiliar work environment, there is a risk that they will perform tasks incorrectly, which could lead to an accident or an injury."