Safety Comes First
John Preston 4025 Peppertree Ln., Silver Spring, MD 20906
This column addresses safety concerns in model aviation activities. The content is the author's opinion and does not necessarily represent the official position of the Academy of Model Aeronautics.
Closing the Book: CA glue
First, let me clarify a statement I made in the previous safety column about alleged cyanoacrylate (CA) glue hazards. I said an article had appeared in at least two model publications alleging health hazards from cyanoacrylate glues. In one of those publications, R/C Report, the allegations appeared as a letter to the editor; Gordon Banks, editor of R/C Report, rightly took issue with my wording. I hope this sets the record straight.
Over the Christmas holiday I visited the National Library of Medicine in Bethesda and consulted the 7th edition of Dangerous Properties of Industrial Materials by N. Irving Sax & Richard J. Lewis, Sr. I searched for ethyl-2-cyanoacrylate (the cyanoacrylate ester most commonly used in instant glues, according to several MSDSs) but found no listing. I then checked methyl-2-cyanoacrylate and found an entry.
Key points from the book:
- Under "Toxicity Data" methyl-2-cyanoacrylate is listed as a human eye irritant.
- When heated to decomposition it emits fumes of NOx (oxides of nitrogen), not hydrogen cyanide.
Based on the book's information and the discussion in the previous column, I do not believe normal hobby use (including incidental heating) would generate quantities of these decomposition products sufficient to cause health problems.
Fingers in the Prop
Photo correction
Russ Pfeiffer (modeler/photographer, Fraser, Michigan) pointed out that a photograph in the December 1990 safety column was printed as a mirror image. The photo showed a bandaged finger resulting from a side‑pusher prop installation. Russ noted three details visible once mirrored correctly:
- The prop appeared to be a conventional CCW‑rotation prop.
- The engine exhaust port was on the left side of the cylinder.
- The bandaged finger (which had looked like the right hand) showed a wristwatch on the owner's right wrist.
Needle‑valve safety: fixed heads, long drivers, and tools
Corpus Christi modeler Ernie Tillman described a simple modification to make some needle valves safer to tune: cut off the head of an Allen socket‑head screw and silver‑solder that cut‑off head onto the end of the needle valve. The idea is to provide a secure surface for adjustment tools and reduce screwdriver slip. It isn't a complete solution but helps. Alternatives and complements include:
- Using a long‑handled socket driver instead of a regular screwdriver.
- Using a Du‑Bro ball‑wrench adjustment tool, inclined away from the prop arc for added safety.
Flexible needle‑valve extensions can still be dangerous
A letter from Thad Byars illustrates a cautionary tale. He bought an AT‑6 fitted with an O.S. Wankel engine that had a flexible needle‑valve extension anchored through the cowling so the valve sat in a convenient, safe location. While tuning the engine in his garage with the cowling off, the needle valve, which he had been holding in a pulled‑back position, sprung back when released and swung into the prop arc. The prop shattered; a 2½‑inch fragment went through his garage ceiling and a tiny adjustment knob was propelled through his wife's Subaru door. He was fortunate to be out of the arc and uninjured.
The next day he replaced the flexible extension with a standard needle valve and then lacerated the end of his left thumb in the spinning prop, requiring stitches. He eventually replaced the Wankel with a .25 and later sold the plane.
Lesson: flexible extensions can reduce risk but introduce other hazards (springback, loose knobs, etc.). Careful installation, secure anchoring, and protective routing are essential — and even then, vigilance is required.
Transmitter‑stick failure
Missouri modeler John Whitsett, Jr., recounts a transmitter failure caused by using K2R spot remover on a plastic radio case. K2R is excellent for removing oil from balsa, and John had used it successfully for that purpose. Some years later he sprayed K2R on the face of a plastic, ergonomically molded transmitter to remove oil and grime. The solvent crazed and weakened the plastic; a small reservoir in the stick attachment area held K2R overnight. During flight the aileron/elevator stick developed so much play that it fell out of the socket, leaving him with only throttle and rudder. He and a club member found the stick on the ground and reinstalled it to land safely.
Moral:
- Do not use K2R or similar solvents on plastic transmitter cases — they can craze or weaken plastic.
- Clean transmitters with cotton balls and Q‑Tips or manufacturer‑recommended cleaners.
- K2R remains fine for removing oil from balsa, but avoid it on plastics.
Runway Safety Barriers
In the January 1991 Safety column I asked whether lowering a runway safety barrier from four feet to three or 2½ feet to improve spectator visibility was reasonable. Responses emphasized that barrier height should match its purpose (protection from airborne models vs. preventing people entering dangerous areas). Summaries from respondents:
- Claude Tanner (Boise Area Radio Kontrol Society, BARKS): Their field uses a 4‑ft chain‑link fence to keep spectators out of the pit area and a 6‑ft chain‑link fence between the pit area and runway. The taller fence appears intended to protect against airborne models as well as grounded ones. Chain‑link can be less obstructive to viewing than some orange plastic fences.
- Gene Corson (Casper Airmodelers, Wyoming): Their field has an 8‑ft orange plastic fence between pits and runway and 3‑ft barriers at each pilot station. Photographs indicate these barriers are no more obstructive to vision than chain‑link.
- Don Johnston (DeLand Radio Control Club, Florida): Their pit area has a continuous chain‑link fence 6 ft high in front of a covered structure and 5 ft high elsewhere. The club (100+ members, including jet and pylon fliers) reports members feel very comfortable with that arrangement.
Takeaway: select barrier type and height based on the level of protection desired (spectator visibility vs. protection from airborne models). Chain‑link fences tend to obstruct vision less than some orange plastic barriers, but each field must balance visibility, protection, and local flying activities.
John Preston
Transcribed from original scans by AI. Minor OCR errors may remain.
