Page 45 - Twin & Turbine May 2017

California Radomes, Santa Clara, California; Nordam in Tulsa, Oklahoma; and Saint-Gobain, formally Norton, in Ravenna, Ohio. It’s possible other facilities in the world have personnel and equipment necessary for proper radome manufacturing and repair, but if so they aren’t widely known.
Field Tests and Repairs
But suppose you operate out of a jungle strip in darkest Africa, or some remote south sea island? Are field tests and repairs possible? Yes, to a limited degree. You begin tests with a simple coin and a “tap” test. A quarter size silver coin will do. With the coin you tap all over the exterior of the radome. Be certain to tap carefully around any openings in the radome, such as those around openings for landing light installations. You’re listening for a musical like “ping”. If you hear a dull clunk anyplace on the dome you’ll have to go plead with your banker for a loan. That “plunk” is telling you there’s a delamination in the radome layers, or water has soaked into the fiberglass, or whatever the radome is made of.
Incidentally, wise pilots also conduct a ping, ping inspection of the radome on every walk around, in case water got into it on the ramp.
With skill and patience it’s sometimes possible to repair a delamination with a fiberglass repair kit; and sometimes possible to dry water out with a hair blower. But without proper testing you can’t be certain your fix was a fix. And a too hot hair blower can blow the entire effort with a meltdown.
with extensive experience in stripping radomes, plus the correct primers and paint for radomes. In some cases, lightning diverter strips will need to be replaced. And, finally, don’t forget about that computerized anechoic chamber for testing.
Here, briefly, is what is required. First, a liquid stripper may not be used. The old finish must be carefully, carefully, sanded off without compromising the base structure. Then a special radome undercoat applied, followed by an odd number of finish coats. After the paint is cured, into that chamber it must go for testing by an engineering inspector.
Continuing with an inspection while the radome is off, check it for pin holes. How? On a bright sunny day point it up toward the sun, stick your head inside and turn it this way and that, searching for any tiny, tiny bright holes. If you find any, mark the location so they can be plugged from the outside with a very small dab of fiberglass or other base material. Very, very small dab. (Incidentally, never apply paint or anything such as an anti-static paint, to the inside of a radome.
Hopefully, your radome will pass all the above self-tests. If not, below are phone numbers for you to contact. Ask first about an exchange for a refurbished and tested one.
California Radomes
Nordam
Saint-Gobain
408-562-1919
918-476-8338
330-298-4105
Assuming you’re lucky and the radome passes the “tap” inspection, next you must check it for transmissivity. This one will require a couple of hours. First, remove radome fasteners, leaving just 2 or 3 to hold it in place. Then power the aircraft up and taxi out to a remote area of the airport. Park with the nose pointed at some prominent building on the far side of the airport, at least a mile or more away, or some building or object beyond the airport boundary. That’s “the target.” Turn your radar on, select the shortest displayed range, full-up tilt. Then carefully decrease tilt until an echo, the target, appears. Adjust tilt to achieve the strongest possible echo from it. Then reduce the CAL control, (probably misnamed “GAIN”) slowly until the target echo is just barely visible on the radar. Then, without changing any radar control, shut down, remove the radome, get back in the airplane and see if that echo has changed. If the target echo is now stronger – even the slightest bit – you have a radome transmissivity problem. Reposition the aircraft left and right and check the target out on the left and right sides of the radome. If that target is brighter – left, right or centered – bad news.
What to do? If the difference, radome on or radome off, is very small, you can take a chance and continue to fly behind it safely. If you are a risk-taker, allow for the slight transmissivity lost you know is there. Advice? Assume echoes with yellow in them actually contain red. Assume an echo showing red contains hail of some size.
But suppose the difference with radome on/off is pronounced? Is a correction in Timbuktu possible? No. Problem is, to restore the radome’s performance will require the services of technicians
May 2017
“Roger that!”
file copy. You can e-mail me at archie@radar4pilots.com. T&T •
For those curious about what DOC-213 says in reference to
radome repairs in Appendix B, I will be pleased to send you a PDF
He’s not a pilot but when
you need to talk about
aviation marketing,
John Shoemaker speaks
House - Roger That
Quarter Page
4/C Ad
your language. And more importantly, he listens.
Call him today and find how the publications he serves, and the markets they reach, can help your aviation related
john.shoemaker@vpdemandcreation.com
business grow.
800-773-7798
VP Demand Creation Services – serving your advertising needs with these fine aviation publications:
● ABS ● Cirrus Pilot ● Comanche Flyer ● King Air ● MMOPA
● Twin & Turbine john.shoemaker@vpdemandcreation.com
TWIN & TURBINE • 43