All UK military Nimrod MR2 aircraft have been grounded as a precautionary measure after a routine safety check uncovered problems with a fuel pipe.
The decision was taken in the last 48 hours after checks on one aircraft, the Ministry of Defence has said.
The fleet was grounded while the issue is investigated but some of the aircraft have already been cleared.
A crash involving an RAF Kinloss-based MR2 in Afghanistan in September should not be pre-judged, the MoD said.
The 12 air force crew, a Royal Marine and a soldier were killed on 2 September when the MR2 came down near Kandahar after a reported technical fault.
The Nimrod was designed as a sea patrol and anti-submarine aircraft and entered service with the Royal Air Force in the UK over 30 years ago.
In the early 1980s some RAF Nimrods were upgraded from the original MR1 design to the MR2, the main roles of which are sea surveillance, anti-submarine warfare and support for search and rescue operations.
http://news.bbc.co.uk/2/hi/uk_news/6390737.stm