Maintenance: Look Beyond Obvious for Wildlife Strike Damage

In the United States alone, there are an estimated 13,000 wildlife strikes each year. The annual cost of these collisions is estimated to be close to $400 million.

When an aircraft returns to base with a cracked or broken windscreen, then the bird-strike damage is obvious. But what about when it isn't?

In helicopter maintenance, we need to pay special attention to the possibility that a bird strike may have damaged the airframe or flight controls – sometimes without the pilot noticing the strike.

The energy created by the bird's mass and the speed of the bird and aircraft during the collision means that even collisions with a small bird (or a flock of small birds) can cause significant damage.

If you see any evidence of a birdstrike – whether reported by the pilot or not – you should investigate further to ensure the aircraft is still airworthy. Most of the time, in helicopter operations, the rotor blades, windscreen, engine inlets, or other forward-facing edges of the airframe are the areas that experience damage in a birdstrike.

In your maintenance inspections, look for damage on leading edges. Note any feathers and snarge (the blood, guts, feathers, or any other remnants of the bird/animal after it has impacted your aircraft), and think about the possible damage that may have resulted.

Be aware that a smudge on the engine inlet cowling might mean that a bird impact has done damage to the cowling or something else downstream. Perhaps it is time to do a power check to see if there is FOD damage to the engine.

This is the season where both large and small birds are moving south. Keep your eyes open for the possibility that they have done some damage to your aircraft.