UK: Great Western Railway has taken some of its Class 800 inter-city trains out of service following the discovery of fatigue cracking in the yaw damper bolsters on a number of vehicles.

The operator has a fleet of 93 electro-diesel trainsets based on the Hitachi AT300 family: 36 five-car Class 800/0 and 21 nine-car Class 800/3 units supplied as part of the Department for Transport’s Intercity Express Programme, plus 22 five-car Class 802/0 and 14 nine-car Class 802/1 units with a higher engine rating ordered by GWR for other routes in conjunction with leasing company Eversholt Rail.


Photo: RSSB

The first cracks were discovered on vehicle 814013.

According to a National Incident Report issued by RSSB, an inspection of set 800 013 at Hitachi’s North Pole depot on April 11 highlighted a crack on vehicle 814013. This was initially thought to be a light surface score which was removed by dressing with emery cloth. However, the cracks re-appeared in the same area and following non-destructive testing it was confirmed that they ‘had substantial depth’.

Following further tests, the NIR confirmed that ‘cracks have been visually identified on the GWR AT300 fleet on the yaw damper bolster. This has currently been identified on eight out of 93 sets. The cracks are in the area where the yaw damper bracket is welded to the car body, with crack depths measured as deep as 15 mm.’


Photos: RSSB

Cracking has also been identified on vehicle 813026.

While the root cause has not yet been identified, engineers note that the majority of cracks have been found on the ‘lead mileage AT300 sub-fleet’, which has led to an initial belief that the problem may be fatigue related. Further examinations, including eddy current testing, are now underway on all bolster locations, while the affected bolsters will also undergo set up and geometry testing.

Similar AT300 trainsets are also in operation with LNER, Hull Trains and TransPennine Express; these operators have been advised of the issue and the investigations that are underway.

GWR told Rail Business UK that ‘as part of the Class 800 fleet’s maintenance programme, hairline cracks have been discovered in areas where the suspension system attaches to the vehicle body on two trains. These have been scheduled for repair. A full inspection of the fleet has identified possible issues on six other units, which have been withdrawn from service as a precaution to allow further investigation. There is no impact on passenger services, which continue to run as normal.’ 

Hitachi subsequently confirmed to Rail Business UK that four of the six units stopped for inspection had now been passed as ‘all clear’ and returned to service, while the two sets originally confirmed with cracks were being repaired. The fleet is being monitored closely while the investigations continue.