I have heard or read something about an auxiliary nose gear downlock switch for the Beech Sierra retract. Can you help with more information or documentation about this.
Technical Editor:
A Beech Service Bulletin, SB 2683, lists a kit for the installation of an auxiliary nose gear downlock switch. This switch is installed in series with the normal wiring for the nose gear down-light. With this kit installed, you will not get a locked nose gear indication unless both the down limit switch AND the downlock-engaged switch have closed the circuit. RAPID has no more of these kits in stock, but if you want to try some other Beech parts places, the kit number is 23-8011-1 (the number in the SB and in the RAPID online inventory), or 23-8011-3 (the number on the card inside the kit). Only the Dash One shows up in the RAPID online inventory system.
The kit consists of the following:
The official drawing with instructions.
Two MS35206-209 screws, which are high-strength, cad-plated, 2-56 thread, Phillips round-head screws, 3/4″ long.
Two MS35333-69 internal star washers (size 02).
Two MS21042L02 all-metal, heat resistant, self-locking, small-hex, washer-head nuts (size 02).
Two M81824/1-1 wire crimp connectors (not worth a crap; used my own better ones).
One 1XE1-3 microswitch with three 36″ long wires attached, molded into the switch.
One JM6 roller-tipped actuating arm for the microswitch.
RAPID lists the 1XE1-3 microswitch itself for $122 in their parts website, but with none in stock (as usual). None of the other items show up in a RAPID search. Having the switch won’t help much without the arm.
There is always a possibility that there is a parted-out Sierra somewhere like Griffin (Atlanta Air Salvage) that has the kit on it. All you would really need is the switch and arm, but getting the small hardware and some length of the attached wire would be gravy.
After two hours of Internet searching (my curiosity got the better of me), I discovered that the 1XE1 is manufactured by Honeywell, and is available from numerous sources. The dash number (-3) refers to the length of the molded-in pigtails; you can make any length work, if necessary. I found a JM5 lever, but not the JM6. I think that the JM6 is a hair longer, but based on my personal experience, and the photos, I believe a JM5 would work much better. The JM6 is just too long for the geometry to operate the switch correctly. Here is a sampling of sources for the 1XE1 switch:
http://www.onlinecomponents.com/default.htm?, 1XE1 (1-foot pigtails) for $46. They also have a JM5 lever for $8
http://www.newark.com/NewarkWebCommerce/newark/en_US/support/search/searchResults.jsp?action=0&First=0&QText=1xe1&x=9&y=4, 1XE1 for $43, or 1XE1-6 (6-foot leads) for $61. They did not show any hits for a JM5 or JM6 lever.
http://www.carlton-bates.com/cb/invsrch/invframe.asp?srchfield=stkmfgpart&vendor=ALL&codevend=ALL&sval=1xe1&submit1=Go, 1XE1 for $43, JM5 arm for $11
This is a page that lists many of the Honeywell suppliers that I was checking through: http://dilp.netcomponents.com/cgi-bin/honeywellsc.asp?partnumber1=1xe1&postal_zip=99999&city=&state=&unit=mi&distance=50&country=United+States
At any rate, if you get the switch and arm, the rest of the small hardware is no doubt available from aviation hardware specialists, though possibly not from an aviation generalist like Aircraft Spruce (it’s too small a size; 2-56 thread). Much to my amazement, AS&S does show the correct screw size in their catalog, but not the washers and nuts. Genuine Aircraft Hardware may have the small hardware. You do need the Mil-Spec hardware, in order to get a strong enough fastener in such a small size.
The drawings are posted on BAC, along with the Service Bulletin that alludes to this modification, since Beech has long since abandoned this part. I can also provide a hardcopy of the full-size drawing (24″ by 48″) to those who prefer to have one for their aircraft records, for the price of the copy and shipping ($10). Any A&P can legally install the kit, with the reference to the Beech drawing and the part numbers, as a minor modification (log book entry only, no 337 or A&P-IA approval required), based on the Beech Service Bulletin.
Technical Editor Addendum June 01, 2009
As an aside, we still seem to have a lot of members flying retracts that don’t understand their safety systems, and who are not verifying that they work. DO NOT RELY 100% ON YOUR SHOP MECHANIC! You should witness for yourself that the gear warning horn works; that the gear safety switch works; and that the gear emergency extension works; all while your plane in on jacks in your shop.
For example:
– We have had two Sierras on which the emergency extension failed. In one case the main gear side brace knees were binding from corrosion on the pivot bolt, and the spring was unable to lock them down. In the other case the nose gear down-lock spring was unable to engage the lock (for multiple reasons).
– We have had two cases in which the gear warning horn was inoperative… and the owner was unaware of its existence.
– We have yet to have a Sierra show up at KLUX for its Initial Annual, with the auxiliary nose gear down-lock switch (called for in Beech SB2683) already installed.
Sierra Down-Lock Switch
Anyone flying a Sierra without this switch is asking for a nose gear collapse. Not because the switch isn’t there; but because the down-lock is not functioning as designed and the owner does not know it. You will get away with it for some period of time; but you will eventually find out the hard way.
Judging by the number of Sierras we see with nose down-lock issues, there seem to be almost no mechanics out there who understand how to test it, and how to repair it when needed. It is nowhere near sufficient to just look at it and see whether it is engaged. You have to watch how it acts during the emergency extension process, and check for free play in the piston rod (where it enters the cylinder). With the plane on jacks and the emergency extension operated, the gear should be down and the nose lock should appear to be engaged. If you can then put your fingers on the piston rod and pull it further out from the cylinder, the lock cylinder has become faulty. That leaves it susceptible to an engagement failure.
There should be no free play at all. The cylinder’s internal spring should exhibit compression resistance as soon as you try to push in the rod. It should take pretty close to 75 pounds of force to fully seat the piston in the cylinder. Most shops will hit you up for a new (expensive) cylinder; but that beats a gear collapse. I am usually able to repair the ones that we work on at KLUX.