The Marine Accident Investigation Branch is investigating the accident. It is understood they are examining a potential wire failure as well as the inspection and maintenance programme for the deck.
Caledonian Macbyrane is checking mezzanine decks on the five west coast ferries which have them.
The MV Isle of Lewis deck has been deployed daily this summer due to the volume of vechicles.
A CalMac spokesman said: "Safety is our number one priority so mezzanine decks are routinely and regularly checked to ensure they are operating correctly and safely.
“In light of this incident we have asked the relevant ships to carry out additional
checks so customers can be assured that we take their safety very seriously."