The Health and Safety Authority (HSA) is carrying out two inquires into the Irish Coast Guard amid concern about life jackets and how its cliff-climbing crews operate.
It comes as three senior Coast Guard officers stepped down at separate stations during the Covid-19 crisis over disquiet about management and procurement practices.
The HSA life jacket inquiry is linked to an issue with a flotation device at a Coast Guard station in Cork which failed to fully deploy.
It was examined by a supplier and correspondence shows corrosion to zips, studs and other materials which were "inevitable over time in a salt-water atmosphere". However, the supplier concluded "there is no safety issue" after carrying out "more than 100 tests on 40 other jackets".
Despite this, all of the life jackets were taken out of use.
The HSA is looking into the matter, while a separate inquiry is examining equipment used by coastal climbing crews.
A Coast Guard spokeswoman said: "Our safety management system deviation process mandates investigation and reporting of events, hence our reports to the HSA."
The HSA said it is aware of matters in relation to Coast Guard life jackets and climbing equipment and "inquiries are ongoing in relation to both".
The Coast Guard is already the subject of another HSA inquiry into the 2016 death of volunteer rescuer Catriona Lucas. She was killed during a search-and-rescue operation off the coast of Co Clare when a boat capsized.
The HSA inquiries are not linked to three Officers in Charge (OIC) stepping down from their roles.
Sources told the Sunday Independent that several OICs, who manage individual Coast Guard units, had raised concerns about how the organisation is being run and the workload placed on volunteers. Concerns were also raised about procurement practices and use of resources.
Earlier this year, the Sunday Independent highlighted how hundreds of thousands of euro was spent on 18 Coast Guard vans that are not capable of carrying a full crew and their equipment at the same time. Each van can carry a maximum load of 3,500kg and was adapted to carry vital equipment used by climbing crews. However, when this work was complete, each van was within 84kg of its maximum load, meaning it could carry a driver but no other crew member - despite having five seats.
"The cadre of 97 officers amongst the ranks of 1,000 volunteers manage the 44 volunteer Coast Guard units around the coast," a spokeswoman said.
"Officers are appointed in their roles for a period of seven years; however, with 1,000 volunteers, there are times when people leave the service for various personal reasons."