While under cover, an improved system was devised for removing Mayfly from the shed.
This consisted of a series of electric winches that could gently ease it out, even in windy conditions, and on 24 September 1911 it was decided to move Mayfly from the hangar for full testing.
Just as the nose cleared the hangar door, a gust caused the ship to roll virtually onto its beam ends.
It eventually righted, but as it was being swung round so that the nose would point back out to the dock, there were cracking sounds amidships and it broke in two.
At that point the centre started to rise, and the crew in the aft gondola dived overboard causing the stern to rise.
Subsequent damage was caused by a bracing cable on the top of the hull, which held fast causing several frames to be severely damaged as the hull was moved by the wind.
There were no fatalities, and the wreck was returned to the shed the same day.

A court of inquiry's conclusion was that no-one could be attributed the blame for the incident, and that it would be reasonable to support the story that the squall was to blame.
It was of such a force that later ships would have also been severely damaged if they had encountered it under the same circumstances.
Commander Masterman is reported as stating unofficially that, "Mayfly was pulled in half by the handling party when someone forgot to release the lines that tethered the bows of the ship."
Furthermore, in an article entitled Twenty-One Years of Airship Progress Lt.
Col.
W. Lockwood Marsh wrote: "This accident, though the ship was undoubtedly weak, was directly due to a mistake in handling, one of the parties on a hawser continuing to haul in without noticing that the after car had fouled a buoy."
While under cover, an improved system was devised for removing Mayfly from the shed. This consisted of a series of electric winches that could gently ease it out, even in windy conditions, and on 24 September 1911 it was decided to move Mayfly from the hangar for full testing. Just as the nose cleared the hangar door, a gust caused the ship to roll virtually onto its beam ends. It eventually righted, but as it was being swung round so that the nose would point back out to the dock, there were cracking sounds amidships and it broke in two. At that point the centre started to rise, and the crew in the aft gondola dived overboard causing the stern to rise. Subsequent damage was caused by a bracing cable on the top of the hull, which held fast causing several frames to be severely damaged as the hull was moved by the wind. There were no fatalities, and the wreck was returned to the shed the same day.
A court of inquiry's conclusion was that no-one could be attributed the blame for the incident, and that it would be reasonable to support the story that the squall was to blame. It was of such a force that later ships would have also been severely damaged if they had encountered it under the same circumstances. Commander Masterman is reported as stating unofficially that, "Mayfly was pulled in half by the handling party when someone forgot to release the lines that tethered the bows of the ship." Furthermore, in an article entitled Twenty-One Years of Airship Progress Lt.Col. W. Lockwood Marsh wrote: "This accident, though the ship was undoubtedly weak, was directly due to a mistake in handling, one of the parties on a hawser continuing to haul in without noticing that the after car had fouled a buoy."
HMA No. 1