A FLEET of planes used on Highlands routes have undergone repairs after crash investigators discovered a faulty harness caused a dramatic nose-down landing of an Inverness-bound plane.

The problem was caused by the use of a cable tie which restricted the flexibility of a moving part of the landing gear system, an Air Accidents Investigation Branch (AAIB) said.

An investigation into the emergency landing in November, 2017 revealed historic issues with the Dash 8 Q400 manufactured by Bombardier Aerospace dating back to the early 2000s.

In September 2007, two separate accidents of similar landing gear failures occurred within four days of each other on Scandinavian Airlines (SAS) Dash 8-Q400 aircraft. A third accident occurred in October 2007, leading to the withdrawal of the type from the airline's fleet.

Fifty-three passengers and four crew members were on board the Flybe flight BE331 from Belfast City Airport on 10 November 2017 which landed without nose gear after it experienced "technical issues" and circled for more than an hour above the Irish Sea.

In the latest incident, crew identified a problem with nose gear and the G-JEDU aircraft was diverted to Belfast International Airport.

Two people suffered minor injuries after the plane landed.

The AAIB investigated and found that a damaged piece of electrical equipment led to the nose gear failing to retract properly and to become jammed in the nose landing gear bay.

The AAIB said the aircraft manufacturer has taken measures to rectify the landing gear problem.

A report reveals that after the crash the operator carried out at an inspection of the nose landing gear proximity sensor harness on its Dash 8 Q400 fleet and undertook "rectification of any anomalies noted".

The most common finding was the absence of rubber lacing, the report found. Other findings included the use of a cable tie in place of rubber lacing, incorrect p-clips and in one case, a damaged NGLK2 harness.

The AIB said that the aircraft and landing gear manufacturers were also working to identify a more flexible harness design which had been initiated before the Belfast incident.

The AIB revealed that issues with the Dash 8 Q400 fleet dated back to the early 2000s, when operators removed large numbers of NGLK1 and 2 harness assemblies due to broken wires.

An investigation at the time identified that the failures had resulted which resulted in the harness "being kinked", as the nose landing gear rotated towards the up-and-locked position. Reported failures occurred between 3,900 and 5,000 flight cycles.

In 2003, the aircraft manufacturer introduced a modification to revise the attachment method for the nose landing gear NGLK1 and 2 harnesses by replacing an existing attachment bracket.

The AIB said: "The aircraft manufacturer advised that the landing gear proximity sensor harnesses are not tracked items and operators that experience problems tend to discard and replace the harnesses."

The report said that the aircraft manufacturer conducted a history search for events relating to NGLK sensors between 2011 and 2018 and identified seven incidents where the nose landing gear interfered with the forward doors during retraction, two of which were the events relating to G-JEDU.

"In all but one of the events the NGLK sensor harnesses were found to be at fault," said the AIB. "In the remaining event, multiple components were replaced but the description of the event and the damage to the NLG forward doors were very similar to that experienced on G-JEDU."

On September 9, 2007 the crew of SAS Flight 1209 en route from Copenhagen to Aalborg, reported problems with the locking mechanism of the right side landing gear of the .Dash 8-Q400 and Aalborg Airport was prepared for an emergency landing.

Shortly after touchdown the right main gear collapsed and the airliner skidded off the runway while fragments of the right propeller shot against the cabin and the right engine caught fire. Of 69 passengers and four crew on board, 11 were sent to hospital, five with minor injuries.

Three days later on September 12, Scandinavian Airlines Flight 2748 from Copenhagen to Palanga had a similar problem with the landing gear, forcing the aircraft to land in Vilnius international airport in Lithuania.No passengers or crew were injured.

Immediately after this accident SAS grounded all 33 Q400 airliners in its fleet and, a few hours later, Bombardier recommended that all Q400s with more than 10,000 flights be grounded until further notice. This affected about 60 aircraft, out of 140 Q400s then in service.

Bombardier were approached for comment.