Installation Secrets
Pre-Installation Inventory
by Butch Nimmo, Tech Rep
Prior issues of the S-TEC Approach featured articles in the "Installation Secrets" column which were devoted to Post-Installation check out procedures (Volume 1, Issue 1, December 1995) and Pre-Installation Planning (Volume 1, Issue 2, March, 1996). Both of these articles have been very helpful to installers since they were published. If you haven't had a chance to read them it would be a good idea to try and find the back issues and review the articles, or contact us and we'll be happy to send the back issues to you.
As an addendum to the topic of Pre-Installation Planning, we would like to discuss the value of the installer taking a Pre-Installation Inventory. In many facilities the receipt and unpacking of our autopilot kit is done in the Receiving Department or the Parts Department. It is not unusual for the system to be handled by numerous persons prior to getting to the installer. Each of these "stops along the way" can be a place for hardware or paperwork to get misplaced. While we go to extraordinary efforts to assure that we ship all the correct drawings and piece parts with the system, we also have been known to err. If you don't catch the shortage until the aircraft is in the hangar and disassembled, an unpleasant installation delay can occur while we get a new part or drawing to you.
Performing an inventory of the contents of the autopilot kit prior to the start of the installation can save time and help you to keep your delivery commitments to the customer.
Each kit comes with a documentation package containing an "aircraft specific" Installation Bulletin, General Installation Bulletin, and Drawings which are necessary to complete the installation.
First, locate the aircraft specific Installation Bulletin. Check to determine that it is the correct bulletin for the autopilot system and model of aircraft targeted for installation. The inside front cover will contain this information at the top of the page. This is a good time to review the "Notice to the Installer" statement at the bottom of the page. Now is the time to identify any potential inconsistencies, which need to be resolved prior to proceeding.
Once it has been determined that you have the correct Installation Bulletin, proceed to reviewing the parts list. The parts list is divided into groups I, II, III, etc. Each group defines a particular portion of the autopilot system identifying the components and hardware required to complete the installation of that portion.
Check and verify that the component and hardware part numbers and quantities match what is required for the installation. If a discrepancy or shortage is discovered we can ship the parts to make the kit complete in time to have a minimal impact on schedules and delivery.
The next step after the major component and hardware inventory is complete, is to insure that the proper drawings are included which define the installation. Section I of the aircraft specific Installation Bulletin gives a step by step description and refers to either specific drawing numbers or the General Installation Bulletin. It is common to have instructions contained in the General Installation Bulletin as well as on one of the drawings referenced by it, which apply to the same installation procedure.
As an installation note, when there are two sets of instructions supplied, most times you do not have a choice. The specific instructions, such as found on a drawing or outlined in the aircraft specific Installation Bulletin, always take precedence over the General Installation Bulletin instructions. One very common installation mistake, which is the result of using the General Installation Bulletin instead of the specific instructions, is locating the altitude pressure transducer behind the instrument panel tee'd into the existing aircraft static system. In many aircraft it should be located in the tail section of the aircraft utilizing its own dedicated set of static ports. This is a common error on all high wing Cessna aircraft. A clean static source is critical for proper operation of the pitch axis of the autopilot.
Each step in Section I of the aircraft specific Installation Bulletin will refer to a specific drawing or to the General Installation Bulletin number. A master drawing list is provided in the aircraft specific Installation Bulletin to assist the installer. At this point verify that all of the listed drawings, as well as the General Installation Bulletin, are part of the document package you received. If there are any shortages call S-TEC's Sales or Technical Support Department immediately so the missing or incorrect drawings can be replaced.
The time spent doing this inventory of autopilot kits can be a very valuable investment.
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