One engine was shut down after a fire warning light was activated on a Loganair flight carrying 46 passengers and three crew from Aberdeen.
Fire crews were called to the airport at around 9.20pm on Wednesday night but were stood down after the aircraft landed safely.
A Loganair spokesman said: “Flight BE6780 carrying 46 passengers and three crew declared a mayday shortly before landing in Sumburgh last night.
“The captain received a fire caution indication from the port-side engine, which was shut down as is standard operating procedure.
“Passengers were briefed by the crew ahead of landing and the aircraft touched down safely.
“Emergency crews met the Saab 2000 aircraft to carry out an external inspection of the engine on the runway, as is procedure. No traces of fire or any other damage were found.
“Everyone on board disembarked the aircraft calmly and without incident.”
The spokesman said engineers are inspecting the aircraft.
Last month, Liam McArthur, Liberal Democrat MSP for Orkney, raised questions at Holyrood about the reliability of Loganair services after a series of emergencies affecting the airline’s flights.
It followed an incident in which a plane travelling from Glasgow to Sumburgh with 13 people on board was forced to make an emergency landing, the second in less than a week.
Responding to the latest incident, Orkney and Shetland Liberal Democrat MP Alistair Carmichael criticised both Loganair and the Civil Aviation Authority (CAA).
He said: “The reliability of our lifeline air services has fallen off a cliff and the number of incidents causing safety concern has increased markedly.
“Public confidence in Loganair is now at an all-time low and they have got to start coming clean with the communities and telling us what is going on here.
“I have it on very good authority that the CAA put Loganair on notice in June of this year about the need to improve their maintenance and support systems.
“In that time the service, if anything, has got worse. The credibility of CAA as a regulator and enforcer of safety standards is now at stake.”