Wayne McDonald 2010
Wayne McDonald was a truck driver at Foxleigh Open Cut Coal Mine near Middlemount. By about 5.15am on the 18th December, Mr MacDonald had completed transporting nine loads of coal, when he called his base and advised that one of his trailers had sustained a flat tyre. His supervisor advised him to drive to a location called "The Mailbox", where the tyre could be changed.
During the process of changing the tyre, a tyre catastrophically failed causing an explosion. Mr McDonald suffered fatal injuries in his chest region from the forces of the blast.
The mechanism of tyre burst was known as a Zipper Failure, named by its characteristic failure mode. It is caused from Fatigue of the steel belts supporting the pressure on the side-walls of the tyre which in turn is caused by running the tyre Overloaded, Under Inflated or Flat for extended periods of time.
This accident claimed the life of Wayne McDonald
- Review of Tyre Management Practices. Initial review followed by annual reviews.
- Tyre jacks have handles of sufficient length to keep operators away from tyres.
- Remote / wireless tyre pressure sensing equipment.
- Tyre tapping not be continued. Tyre pressures determined using accurate gauges.
- Tyre standards be updated or created.
- Documented advice from tyre supplies for dispensation from designed operating parameters.
- Dispensations from suppliers included in training and operating procedures at mines
- Dispensations from suppliers be permanently embossed on the sidewall of the tyre.
- Integrity testing of tyres.
Wayne McDonald - A Miners Legacy http://www.aminerslegacy.com.au/legacy-page/wayne-macdonald/
Zipper Failure
The typical signs of fatigue – wrinkling or discolouration of the inside walls of tyres, are not always present. This tyre was examined by an expert tyre fitter in Mackay prior to the incident (to fix the “slow leak”) and by a range of experts after the incident and NO signs of fatigue were evident – yet it did fail from fatigue. The fatigue may have been caused by operating the tyre under-inflated during the time it had the “slow leak” or it may have been run as a companion tyre to a flat tyre [the trailers are all dual wheel configuration] or it may simply be due to the industry wide practice of checking tyres by “sounding” or “tyre tapping” them with steel bars – a universal practice but hardly a calibrated means of ensuring correct inflation.
Again, however, all of this is secondary to the fact that there exists NO fool-proof means for detecting potential fatigue of steel belted Light to Medium radial truck tyres. No technology exists, no inspection system exists and no universal signs and symptoms will always be present to indicate fatigue. The only documented means of protection that could be located was recommended by American Trucking Association which have published a Recommended Maintenance Practice Manual RP 232 Zipper Rupture Inspection Procedures for Light and Medium Duty Truck Tires
This procedure recommends that, following repair or suspected Run-Flat, the tyre be subject to staged inflation to 20% above its operating pressure and then waiting & listening for 20mins for signs of the steel belts failing. This process suggests that if the tyre was going to burst from fatigue, it would burst during this over-inflation process but within the “safe” confines of an inflation cage.
http://www.tirelitigation.com/failure-modes.html
http://www.bridgestonetrucktires.com/us_eng/real/magazines/ra_v15i1/ra_doc.asp
News Article - Mining Australia
A coronial inquest in Queensland has heard Wayne McDonald died due to a “zipper failure” which caused a tyre to explode. Wayne Robert MacDonald, 53, was killed at the mine in 2010 after changing a tyre on a trailer attached to a prime mover.
MacDonald was working as a truck operator for Brisbane-based company LCR, a position he had held for over four years.
The inquest heard MacDonald inflated the replacement tyre to 110psi, Daily Mercury reported.He was still under the trailer when the replacement tyre exploded. John Aberdeen, Counsel assisting Central Queensland Coroner David O'Connell, said the "inner side wall of the inside tyre" failed in what was called a "zipper failure".
The tear in the side wall "was sudden and catastrophic" resulting in a "powerful torrent of air" escaping, he said. MacDonald suffered the full force to his chest and upper body and died at the scene.
As part of an investigation by the Mines Inspectorate, the tyres of four prime movers at Foxleigh mine were examined. Lead investigator John Sleigh said there was "a great deal of confusion" from workers at the site as to the correct tyre pressure level. A range of figures were assumed including 100, 110, 120, 125 and 130psi with the inquest hearing any over or under inflation of tyres can compromise safety. Sleigh said he did not examine the pressure of the tyre of the vehicle involved in the incident following MacDonald’s death.
He said a forensic examination of the failed tyre showed a previous slow leak repair and the zipper failure were not connected. MacDonald’s wife, Pam, said her husband was "let down by his employers". "Wayne was hard-working, nothing was too much trouble, he loved life and he was my life," a read out at the inquest said. "The pain and hurt I've to deal with and (am) still dealing with cannot be put into words and I just hope it doesn't take another fatality for changes to continue.
"If something good has to come out of all of this for those who work in the industry, then I feel Wayne's life has not been wasted." The coroner asked Dunlop, Anglo American, LCR and the CFMEU to submit agreed recommendations by June 20.
Source - www.miningaustralia.com.au