Hellraiser

An accident involving a Jackson Matterhorn amusement ride belonging to Walter

Shufflebottom.

David Rudland

HM Specialist Inspector of Health and Safety – Mechanical Engineering.

Hellraiser

The ride following the accident

The ride following the accident

The ride following the accident

The ride following the accident

The ride following the accident

Broken tie bar

The main drive frame had lifted from the bed of the trailer – all four welds had broken

The ride was built by Jackson in 1976 as a Cresta Run and re-built in 1983 as a Matterhorn.

Decision was made to take possession of the ride. It was labelled, dismantled and transported to a secure site at Eye for further

examination

• The main structure was held on the trailer

• The passenger cars, frames and tie bars were stored in a warehouse building

The owners were requested to visit site, and partly erect the ride to permit further examination

The ride was built around a large articulated trailer, and consisted of an undulating track, referred to as the tram. This was built up on outriggers extending from the trailer. At 2 points the tram passed over the trailer.

9 frames ‘A’ to ‘J’ were equally spaced around the central drive turret. The wheels on each frame rested on the tram.

Ride layout

• 9 frames ‘A’ to ‘J’ were equally spaced around the central drive turret. The wheels on each frame rest on the tram.

• Cars 1 -18 were suspended from the frames

• Each frame was linked to its neighbour by means of a tie bar (not shown)

• Drive sub frame at position A provided the main drive.

• Only frame A was held in the correct position by its drive sub frame

• The other frames were held in position by the tie bars.

• The cars contributed little due to a hinge on the suspension tube, and the orientation of the couplings

Significant damage was caused by the accident.

• A number of cars were badly damaged.

• A number of the tie bars were badly damaged.

• A number of the tram support pillars were bent.

• Chains and shackles securing the cars were bent and broken, and their mountings were also damaged.

• The central turret welds securing it to the trailer were all broken.

• The display boarding around the tram was partly destroyed.

• Other superficial damage was seen.

General condition of the ride.

• The ride was found to be in poor condition

• Many faults and evidence of inadequate maintenance were identified

• Some examples are shown on the following slides.

Worn out dampers, worn pins and location brackets

Missing seat retaining nuts

Seized/jammed hinges on car suspension tubes

Cracked and broken welds found all over the structure.

Cracked and broken welds found all over the structure.

Sub standard weld repairs to the main outrigger structure

Poor quality modifications to tram support uprights

Metal removed from drive turret support fabrications

The right hand drive sub frame mounting bracket, welded to the turret top plate showed signs of damage, and cracking around the frame mounting hole. When comparing this bracket to others on the turret, it appeared that at some point, a repair or modification had been carried out.

Poor quality electrics – exposed cables, no door on the main electrical cabinet, which had tools and other debris stored within it.

In addition

– Totally unguarded diesel engine and drives to the hydraulic pump

– Lose ball hitches– Leaking hydraulic rams on the trailer

legs– The ride did not run centrally on the

tram– Etc..

Tie bars

• The tie bars form the integral links between the 9 frames, and hold the ride together.

• The tie bars were in extremely poor condition– Evidence of repairs/ strengthening– At least 4 different types of coupling identified– Evidence of cracks and damage in the ball

cups– Evidence of cracks and damage in the area of

the mounting holes– Different mtg methods used, some with added

weld.– The bars were of different length with no

indication where each should be located.

Coupling / Hitch

Evidence of repairs/ strengthening

Evidence of cracks and damage in the ball cups

Evidence of cracks and damage in the ball cups

Different mounting methods used, some with added weld.

Only one fixing bolt used, and fractures seen around both mounting holes.

Holes had been repositioned when replacement hitches had been fitted.

Holes had been repositioned or slotted when replacement hitches had been fitted.

A hitch removed from a tie bar.

• The evidence suggested that the tie bars were being subjected to loads greater than that for which they were designed.

• The repairs, damage, and 2 further discarded couplings found on the ride suggested that this had been an on going issue.

• It was clear that the bars were different lengths, the holes positions were different, additional holes had been added, coupling of different ages and types were fitted - all suggesting that modifications had been made to the tie bars over a period of time

• HSL were able to establish– On many hitches, a sequence of up to 6 layers of paint

over the ‘repairs’ suggested their existence for a number of years.

– Cracks were seen with paint on adjacent faces, under several layers of paint suggested some cracks had been existence for years rather than months.

– Successive layers of paint over the bolts suggested they had not been dismantled for inspection and detection of cracks around the fixing holes.

– Successive layers of paint suggested that NDT had not taken place for many years, if at all.

– The wall thickness on the ruptured cup was approximately 25% of that seen on a new unit in the rupture zone.

• The tie bars were not of uniform length, and no markings were found to suggest each had a fixed location around the ride.

• None of the tie bars included a mechanism by which its length could be adjusted. It was therefore probable that an amount of ‘slack’ existed in the system to permit assembly of the ride.

• The tie bars showed evidence of having been subjected to various modifications and repairs, over an extended period of time. No records of any modifications were found, and there was also no evidence that the modifications had been checked and approved under the ADIPS scheme as required.

The accident was caused by a failure of a coupling on a tie bar.

• Tie bar (2) between frames ‘A’ and ‘B’ failed, which triggered a sequence of events cumulating in the failure of the ride.

• Tie bar (18) was then effectively ‘towing’ 8 frames and 16 cars around the tram. As a consequence it also failed.

• With nothing to hold them in place with frame ‘A’, the frames fell back.

• The wheels on frame ‘J’ and others dropped inside the tram leading to a jam which quickly stopped the ride.

Failed Tie bar

• The ball coupling on tie bar (2) had been ripped from the box section.

NDT

• There was an NDT schedule.

• There was evidence that NDT had been carried out on the areas indicated on the schedule.

However

• The NDT schedule did not require NDT to be carried out on the tie bars, couplings and balls, despite this being one of the most highly loaded areas on the machine.

• There was no evidence that NDT had been carried out on the tie bars, the couplings or the balls.

Drive sub frames

• Evidence was found that at some point in the past, the ride had been fitted with a 2nd drive frame. The mounting brackets were welded to the turret, and one of the frames was also fitted with the required brackets.

• No evidence of the frame itself was found.

• When fitted with 2 drive frames, the loading on the tie bars would have been much less than when only a single drive frame was in place.

Mountings for the 2nd drive frame

Summary

• The evidence suggested that at some point in its past, the ride had been fitted with two drive sub frames. When fitted with two drive sub frames, the loading on the tie bars would have been much less than when only a single sub frame was in place. Thus, it was likely that the tie bars, and their couplings were being subjected to much higher loads, ultimately leading to their failure.

• The ball couplings on the tie bars were only rated at 750 Kg. There was evidence to suggest that it was likely that the load being applied to the couplings exceeded this value during normal operation of the ride.

Summary

• The ride was in very poor condition, many faults and evidence of inadequate maintenance being identified during the investigation. These can be broken into 2 areas:– Inadequate maintenance.– Inadequate repairs/modifications

Summary

• Successive inspections of the ride:• failed to identify that significant

modifications had been made which could have an impact on the integrity of the ride, i.e., the removal of the 2nd drive sub frame.

• failed to identify the significance this modification would have on the tie bars

• failed to recognise the very poor condition of the tie bars, and the repairs/modifications made to the press steel ball couplings

• failed to recognise other areas on the ride which were in a very poor condition.

Recommendation

• Before being put back into service, it was recommended that the ride was subjected to a full design review, which took account of the loading on key components such as (but not limited to):

• The central turret and its mounting to the trailer

• The drive sub frame(s)• The tie bars and the pressed steel ball

couplings.• The cars and their mountings

• In addition, a full inspection of the ride should be made to provide a full list of items requiring attention following the accident.

Prosecution

• At Ipswich Crown court - 30/11/09 - Case heard by judge Goodwin. – The ride owner, Mr Shufflebottom was convicted and fined

£2000.00 . – The ride examiner, Mr Meakin , was convicted and fined

£2000.00 plus £1000.00 costs. – Fairground Inspection Services were convicted under Section

3(2) and fined £8,000.00 plus £1000.00 costs.

• Although these fines appeared modest they were significant when the means of the defendants were taken into account. The ride owner for example had no assets, lived in a caravan on an old age pension and has not been able to use his ride since the accident.

• The judge was damming in his sentencing remarks and referred to bodged repairs and an accident that should not have happened.