Are you looking for Mean Time to Repair, or Mean Time Before Failure? ( MTBF )
MTTR is variable as the level of repair can be a simple non-supervisor blade replacement or a more complex chassis replacement. It depends on the model in question and what it would take in any particular environment to repair/replace failed systems/components.
MTBF is what Cisco publishes on it's product line.
See and example:
http://www.cisco.com/en/US/customer/products/hw/switches/ps708/products_data_sheet0900aecd802b647c.html
Cisco published MTBF numbers often go upwards of 100,000 hours and are expressed in years in some cases.
Hope this helps.
