The Ground Handling Blog

Mototok's blog for Hangar Professionals

Written by Mototok on November 29, 2017 // 4:30 PM

Hangar rash prevention: A step-by-step guide


Unlike many pieces of machinery, most notably automobiles, airplanes and aircraft are an investment which generally appreciates over time. Aircraft are also subjected to some of the most harsh and unforgiving environments on earth, from baking in the summer sun to flying thousands of meters in the freezing atmosphere, often times within just minutes of each other. These machines are engineered to endure such extremes and do so very well; what they are not designed to endure are the dents and dings which are commonplace to ground movement, or “hangar rash”.

What is hangar rash?

The definition of hangar rash is essentially minor damage caused to an aircraft during the ground movement stages of operation, particularly damage sustained in and around movements in the immediate vicinity of a hangar. The Flight Safety Foundation (FSF) held an initiative title the Ground Accident Prevention initiative, and this found that there were around 27,000 ground accidents annually, which amounted to one per every 1,000 departures. These events amounted to $10 billion in annual damages, most of which were costs absorbed by the owner/operator as they fell below the threshold for insurance claims. Many of the incidents noted by the FSF were on the ramp area, so they may not necessarily fall under the definition of “hangar rash”, but the atmospherics leading to the damage is essentially the same. Hangar rash generally implies the aircraft inadvertently being pushed or pulled into an object during ground movement, or even more common is ground support equipment (GSE) coming in contact with the aircraft. This could be anything from powered GSE (power carts, heaters, etc.), to ladders and maintenance stands (very common culprits). The cost of damage done by a ladder falling or scraping paint from a careless act is staggering.

Risks of hangar rash: physical and financial

Risks of hangar rash may be viewed in two distinct categories: physical and financial. The physical risks of hangar rash can honestly be just about anything in the hangar: hangar doors, aircraft tugs, ladders, tool boxes, personal and utility vehicles, etc. Baggage handling equipment, food service carts, and even lavatory service carts have left their mark on aircraft before, and will surely continue to do so for as long as man takes flight. In our professional experience, the ground movement of aircraft into a fixed object tends to be the least common infraction; heavy items on wheels are very common. It only takes a matter of seconds for a tools box to roll into the leading edge of a wing or fuselage skin. In the blink of an eye, a vehicle can drift out of the driving lane and into an aircraft. A vehicle left in neutral without properly set brakes can roll right under an engine nacelle.

The financial risk involved in hangar rash may vary greatly, but one thing is certain: it will not be cheap. It is impossible to give accurate estimates because every structural repair is different from one to the next, but the cost really mount on structural damage since structure repairs are not just “box swapping” like avionics or exchanging components as in engine and accessory repairs. Structural repairs must be evaluated on an case-by-case basis since each incident is different. If a hydraulic pump fails, the repair process is fairly simple: replace the item with a like item. But skin and structural damage requires a much different approach.

For instance, assume that an aircraft was accidentally towed into a fixed object, such as maintenance scaffolding, and a hole was punched into the forward fuselage. At first glance it appears that a patch panel will need to be affixed to the hole and painted, end of discussion. The process is not quite so simple, though. Depending on the depth of the hole or dent, the size of the contusion, and the location in relation to bulkheads or stringers, a non-destructive inspection specialist may be required to conduct an eddy current test on the area to determine the depth extent of the damage. What appears to be wrinkled skin may end up becoming a repair in the tens of thousands to millions in repair cost, as well as the lost time in commission of the aircraft. All of this due to careless ground handling or lack of situational awareness during ground movement.

Common mistakes which lead to hangar rash

Whereas there are circumstances outside of the control of human action which cause incidents in flight, hangar rash is always the result of human error. The very nature of hangar rash stipulates that there be a party which has done something which ultimately causes damage to the aircraft from an external force.

A very common mistake leading to hangar rash is the improper parking, mooring, or braking of mobile objects. And addendum to this would be properly braked and moored equipment but that is in poor condition. You could not even begin to place a number of occurrences of mobile support equipment and vehicles simply rolling into a parked aircraft. The old adage goes “there are rules because somebody did it”, and the aviation community is no exception. U.S. Air Force aircraft maintenance schools spend several hours on the proper way to castor and brake wheels on powered and non-powered ground support equipment (e.g., maintenance stands, heaters, power units) because there have been so many incidents involving support equipment.

Tool boxes are a notorious culprit and maintain the capacity to cause a whole lot of damage. Tool boxes are extremely heavy, have castering wheels, and sharp edges. Many fuselages have been penetrated by a carelessly parked tool box, or by a mechanic who ‘just had a quick fix’ and did not take the time to set the brakes. The most succinct answer is to correct careless behavior and develop an active plan and program to promote a safe culture.

Avoiding hangar rash: 4 easy steps

So are there any proactive preventative measures that can be taken to avoid hangar rash? Yes, because hangar rash is always an active occurrence. The process is very simple: get back to the basics of ground handling and housekeeping.

  1. Become familiar with your surroundings. Get to know the hangar, the apron, the tow-ways and taxiways. By “get to know”, this means get out a measuring wheel and determine clearances down to the inch. In the business of moving aircraft, inches do matter. Finding a competent paint contractor to paint guide lines into and inside of the hangar is a very good expenditure that would more than pay for itself if only a single incident were avoided.
  2. Check and double-check the small things. It takes only 30 seconds or so to properly caster and lock a wheel and set the brake. Conversely, the aircraft can be down for months for the associated repairs. While Foreign Object Debris (FOD) damage is not necessarily hangar rash per se, it follows the same line of action. It only takes a second to pick up a stray piece of hardware, but that stray hardware can cause tens of thousands in damage, not to mention putting lives in jeopardy.
  3. Use the right tool for the job. The simplest measures are setting brakes, looking where you are going, making sure that the area is properly policed. But sometimes there is just no substitute for having the right tool when you need it. Moving a light passenger airplane is one thing, but moving a Gulfstream in and out of a hangar is quite another. When moving aircraft of that shear magnitude (and cost) around very tight quarters, it pays to get the best tool for the job.
  4. Triple check. In all seriousness, check the brakes on everything, and triple-check the clearances. An ounce of prevention is worth a pound of cure.

Hangar rash prevention needs the right tools

Much of hangar rash prevention is just basic situational awareness. That being said, it is worthwhile to invest in tools to level the playing field. Aside making sure that rolling tool boxes, tool caddies and other assorted ground support equipment are of high quality and proper working order, the aircraft tug which you choose to use is the one piece of equipment which carries by far the most liability. Traditional tractors have outlived their usefulness for most applications, being outshined by far more maneuverable, efficient, user friendly, and most importantly, safe remote control units. These machines offer much needed functionality which simply cannot be rivaled by tractors:

  • Remote controlled electric tugs stop instantly, as opposed to tractors which often take several feet. Also, the tow supervisor is operating the remote control so there is no lag between him commanding to stop and the tractor operator executing the command.
  • Remote control tugs allow the operator to walk to any part of the aircraft during movement, rather than being tethered to the aircraft and remaining sometimes in excess of one hundred feet from the critical phases of the operation (empennage, wing tips).
  • Since the remote control tug is very low profile, it allows the aircraft nose landing gear to be essentially on top of the tug, allowing unsurpassed maneuverability and visibility.

Conclusion to preventing hangar rash

Hangar rash is a disaster which is thankfully completely preventable. However, the damage done by careless behavior in the hangar environment rivals that of non-preventable disasters, to the tune of $30 billion per year. This is a very bitter pill to swallow when you realize that it is completely and totally preventable. Aside simply getting back to the basics, giving yourself the cutting edge of aircraft movement equipment is the best defense against hangar rash. Do not give yourself any more chances to suffer the consequences of using an inferior tool for the job; step into the 21st century with a modern electric remote tug.

Preventing hangar rash is the first step to a better and safer ground handling. Read even more tips in our free eBook!

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