View Full Version : Hangar Vs Line Maintenance
I'd like to get some information regarding performing maintenance tasks in a hangar (under heavy maintenance conditions) as apposed to performing them on the line. For instance:
1. Routine Maintenance - Operational or Functional Checks
2. Modifications - Service Bulletin embodiment
The reason I ask is that I have not a lot of experience with this type of work, however it is something I would possibly like to experience in the future. You may assume (from my user name) that I have some experience with manufacturers maintenance documentation.
I have seen invoices for maintenance performed on checks, and the numbers sometimes don't add up. Don't get me wrong, I do know that hangar maintenance moves at a different pace than line maintenance, but how do you know when people are taking the p*ss?
For instance, a 20 minute battery change can cost an hour in the hangar. Do they charge you for the person going to the stores, taking the part to the aircraft, changing the part, returning the old part to stores etc?
Likewise, a 40 minute component change and function check can cost up to 2 man hours work in a hangar!
Service Bulletins - Do all hangars apply a 'factor' to the manufacturers recommended time for embodiment? Is 1.5 the norm?
Sorry if the question is a little naive, but I'd like to have some insight into the whole commercial side of how it's all managed and agreed. :confused: :suspect:
MPD,
Some would argue your comment that hangar and line mx operate at a different pace.
The simple fact is that on the line the system is geared for replacement, etc. If a componant change is required, the relevant manual pages are printed, stands, parts, etc made available so that when the a/c arrives on stand, the job can start as soon as possible, resulting in minimum downtime. There are (usually) enough bodies to do the job and if a duplicate inspection is required, an appropriately licensed engineer is available to carry it out immediately. More often than not the person carrying out the task will certify it too.
In the hangar the task is assigned probably to a mechanic/fitter and he/she "clocks on" to the job. They then have to access the MM to establish what the task involves and what tooling will be required, a/c configuration, etc. They then have to provide access (steps, stands,etc). Now they get the part from stores or the preload shelves (only to find on their return that some toe-rag has moved their steps to do another job :} ) Now the part is replaced, the old componant is labeled and returned to stores and the paperwork signed on the job card. The fitter can then clock off the card.
Notice that there has been no inspection or function check yet!!:hmm:
At some later stage, when power is available or when it is safe to operate the replaced componant. An inspector will clock on to the card. They also will have to check in the MM to see what was done and how to function it. They will then carry out the inspection and then (possibly with the help of another engineer for safety reasons) do the function check before signing the relevant documentation and clocking off.
So you can see the process is bound to take longer, although the actual time spent working on the a/c will be pretty well the same.
As for SB's etc. The time quoted on them (for Boeing at least) quite clearly states that it does not factor in job preparation, access, tooling and so on. So again there will be some discrepancy.
Hope this helps. :ok:
Blacksheep
21st Feb 2005, 03:51
The above is more or less accurate but a tad simplistic.
Line Maintenance is customarily covered by a contract that specifies exactly what service level is provided. The contract will incorporate a rate for 'additionals' such as wheel/brake unit changes, defect rectification etc. but the aircraft will have manpower allocated for the duration of the visit. Materials are typically charged 'per use'. Thus the 20 minute battery change that you mention covers only changing the battery. All the other time involved may be absorbed in the overall contract. The part should be already available at the stand (but isn't always there!) when the aircraft arrives and is then replaced by the transit crew already allocated to the aircraft for the duration of the transit.
In the Hangar, maintenance is costed on a per job rate. There is generally a fixed price for the complete routine check, with defect rectification, Service Bulletins and other additional work (such as battery changes and so on) charged on actual time consumed. Thus the charge for an additional job covers all the steps involved in getting the job done. Several people will be involved in any one hour of labour - storekeepers, planners and mechanics - not necessarily the one man who wields the tools. The charge will then cover the total manhours expended on the task.
When estimating the time that will be needed to accomplish a Service Bulletin the planners will assume a fixed factor of 1.5 or even 2 times the standard time given by the manufacturer in the bulletin. The SB standard time assumes all access already open with stands in position; tools, materials and documentation pre-positioned ready at the work location and all manpower briefed and familiar with the task. The planning estimate is not used for invoicing: The bill will be for the actual manhours consumed, including all the fetching, carrying and reading.
Thanks for the replies. Didn't mean to imply that there was a different work ethic in the hangar than on the line, nor upset anyone reading the forum. :O
It's just that I am still a little confused. If the work pack is prepared and ready for the check, if there is a set price for talking the aircraft into the hangar, jacking, cleaning, access, and installing the stands required IN ADDITION to the fixed price for the check - why such a vast difference in the cost of the additional work? :confused:
With regard to SB embodiment, I appreciate the fact that the estimate will assume the aircraft is in a maintenance state with all access etc. However, if you have access during the check, do you still pay the 1.5 factor? If you do, why? Surely this doesn't make sense commercially, or is it just industry standard?
Maybe I'm just getting cheap in my old age... perhaps I should change my registered name to SKINFLINT??? :8