BY SAM SYMONDS
The U.S. commercial aerospace industry has taken a more determined step in the direction of repairing electrical wiring harness products as opposed to replacing with new. This is a direct result of how the world has changed. Challenges that began September 11, 2001 have been magnified due to the recent energy crisis and ongoing economic downturn.
Not that many years ago, U.S. airlines, both large and small, either had the in-house shops to repair components themselves or replace them with new aftermarket spares, disregarding the cost. With airlines now just trying to survive, this is no longer the direction being taken. Today, airlines are trying to outsource more of the maintenance to reduce costs. There is an advantage to this as there are many reputable Repair Stations in the country specializing in almost every component on the aircraft and/or the engine.
 FIGURE 1. A technician applies a nickel overbraid to a wiring harness for added chafe protection. |
While this benefit can be enormous for the world’s airlines., where the new “rub” comes is in the component maintenance manuals (CMM) and what the component’s Original Equipment Manufacture (OEM) wants to allow their customers to repair.
A small minority of product is manufactured as “non-repairable,” and for a couple of good reasons. First, it may truly be cost-prohibitive to repair, meaning it would cost more than it’s worth. Second, the proprietary nature of the item may require constraints. No one can blame a manufac- turer that is trying to protect trade/design secrets.
But the vast majority of items found on the aircraft are repairable. With the industry fighting so hard to rebound, or to just survive, another alternative, such a a Repair Station, is needed.
A Repair Station can accomplish much with great quality and reliability. One that is also an OEM has the ability to perform repairs that would normally only be done at the OEM level; therefore, it is able to pass on a real savings to the operators.
Most aftermarket replacement items are very expensive due to the nature of single-piece purchases versus quantity buys. In addition, a repair sent back to the OEM is generally thrown into the “production” process flow. This can create a tremendously long turnaround time.
An experienced, well-disciplined Repair Station, however, can perform specified CMM repairs as well as write the procedure and perform the same repairs that would normally be done at the OEM factory. This can typically be accomplished in far less time.
The mechanism to make this happen is either approval from the airline’s engineering (which is just as busy as the FAA engineers) or a DER approval–an FAA certified Designated Engineering Representative. These individuals have many years of experience with the airlines or manufacturers, and have worked closely with and are certified by the FAA. They do the painstaking analysis that the FAA engineers don’t have the time to perform.
Electrical wiring harnesses are especially suited for this scenario. Many engine harnesses are covered with an outer braid layer for chafe resistance. The harness OEM is selling these harnesses to an engine manufacturer or, in the aftermarket, to an airline. The OEM has to write a CMM to support their product, but knows that neither of these customers have the means to braid new material on the outside of a worn harness. So, he states that if something over a minimum acceptable amount of abrasion has occurred, the harness is either scrap or needs to be sent back to the manufacturer for repair.
A third-party Repair Station with the proper equipment can come to the rescue at this point and write a repair procedure to strip and re-braid the harness. This, of course, has to be approved by the airline or a DER, but the benefits can be significant.
 FIGURE 3. A Repair Station technician performs a final inspection on a repaired wiring harness before its return to service. |
Most OEMs have in-house certified repair stations for processing returned product. The catch is, in many cases, these organizations depend on support from different areas of production (i.e., harness braiding); so, the OEM doesn’t have to duplicate equipment. This can and does have a tremendous impact on turnaround time.
There can be a significant cost associated with a return to the OEM as well, because the repair station technicians are generally the best all-around technicians in the organization. In most instances, this translates to being the highest paid technicians coupled with standard production rates, and a very expensive repair to go with the long turnaround time. A third-party repair station being run as a separate business can usually turn the parts around faster at a far more palatable price.
Over the past several years, Parts Manufacture Approval (PMA) parts have been brought under closer scrutiny for fear of meeting the intended requirements. Where these two scenarios differ is that repairs are still predominately governed by the OEM CMM, and there is not entirely new documentation. When the repair station and the DER have completed their justification, the product truly is as if it were repaired in the facility in which it was manufactured.
If an aircraft operator wants to save time and money, they need only look for a FAA-certified Repair Station with expertise and initiative. CS
SAM SYMONDS is president and CEO of Co-Operative Industries Aerospace (www.coopind.com), a Fort Worth, TX designer and manufacturer of electrical wiring interconnects, ignition leads, and flexible conduits for airframe, engine, ground support equipment, and space applications.
