October 2014-
Though it is rare, it does happen. It happened to me just last week.
It was the first day of August. I was flying a pressurized twin to Canada as part of the sale to the new owner, and he was with me at 21,000 feet. We were picking our way through a line of weather. The radar and NEXRAD showed us a safe distance from any major convection.
We had just started our descent to our fuel stop when we encountered precipitation static. If you’ve never heard it, it’s a loud screaming sound on the radio that builds in volume and intensity—and abruptly stops when the static discharges. It’s not exactly uncommon.
Just as the static stopped, a loud explosion and a flash filled the windshield. I didn’t think it actually hit us, but the lightning sensor on the Stormscope was indicating failed. Otherwise, everything else was normal.
We proceed to land, take fuel and have lunch. The rest of the trip was pretty routine, though the weather was pretty crummy.
A pre-buy discovery
Later, during the pre-buy inspection, the lightning damage was discovered. It had struck the radome and through the nosegear door; it had “crawled” down the fuselage and exited at the top tip of the tail. Along the way, it fried the antenna for the Stormscope.
Total cost to repair (including the antenna, which alone was $1,500), was just over $4,000.
Before you tell me, “I don’t fly a pressurized airplane and I don’t go that high,” know that it doesn’t matter. Though lightning strikes are rare, they do happen.
The insurance adjuster, Bill Arnold, a retired U.S. Air Force pilot and current director and general manager of Arnold and Arnold, Inc., shared his knowledge with me regarding lightning strikes. He told me what he’d learned in the Air Force: it wasn’t how close you are to the thunderstorm, it’s how close you are to the freezing level that makes all the difference.
“The AIM tells you to stay 20 miles away from a thunderstorm,” Arnold said. “Most of us get a lot closer than that.
“That’s fine if it’s well above freezing,” he continued. “But the closer you get to the freezing level, the more distance you need to put between you and the thunderstorm.” In 35 years of flying, I’d never heard that piece of wisdom.
Inspection data
Some aircraft have specific inspections for lightning strikes, but most General Aviation airplanes do not. The FARs don’t offer much guidance on this topic, either. Part 43 says this:
Although lightning strikes to aircraft are extremely rare, if a strike has occurred, the aircraft must be carefully inspected to determine the extent of any damage that might have occurred. When lightning strikes an aircraft, the electrical current must be conducted through the structure and be allowed to discharge or dissipate at controlled locations. These controlled locations are primarily the aircraft’s static discharge wicks, or on more sophisticated aircraft, null field dischargers. When surges of high voltage electricity pass through good electrical conductors, such as aluminum or steel, damage is likely to be minimal or nonexistent.
When surges of high voltage electricity pass through non-metallic structures, such as a fiberglass radome, engine cowl or fairing, glass or plastic window, or a composite structure that does not have built-in electrical bonding, burning and more serious damage to the structure could occur. Visual inspection of the structure is required. Look for evidence of degradation, burning or erosion of the composite resin at all affected structures, electrical bonding straps, static discharge wicks and null field dischargers.
As you can see from the pictures, it can and does happen—hopefully, not to you.
This is the third time in three and a half decades and thousands of flight hours that an airplane I’ve been piloting has been struck by lightning. Even if you’re using a tactical tool like a Stormscope, my recent experience shows that you can still be surprised by lightning. Always keep a safe distance between your airplane and the weather, and if it’s close to freezing, make sure that distance is even greater.
Michael Leighton is an 8,400-hour, three-time Master Flight Instructor, as well as an A&P mechanic and former FAA Accident Prevention Counselor. He operates an aircraft maintenance and flight training company located in South Florida and Spartanburg, S.C. You can find him on the web at flymkleighton.net. Send questions or comments to editor@www.piperflyer.com.
