747 lightning strike inspection

On average, every commercial aircraft is struck by lightning once or twice a year. After the aircraft lands, an inspection must always be performed to assess the state of the aircraft prior to return to service. The Boeing 747 is no exception and here you will learn the ins and outs of lightning strike inspections performed on this aircraft type.

The Boeing 747 is a large, long-range wide-body airliner and cargo aircraft whose origins go back to the late 1960s. After introducing the 707 in October 1958, Pan American World Airways (Pan Am) asked Boeing to design an aircraft 2½ times its size, improving the capacity. The development of the 747 began in April 1966, led by Boeing engineer Joe Sutter, who has previously worked on the 707 and 737. The first flight took place on February 9th, 1969, and the 747 was certified later in December. Dubbed as “Jumbo Jet” the first twin-aisle aircraft entered service with Pan Am on January 22nd, 1970. The 747 and its increased capacity soon became iconic, democratizing air travel.

How often is a Boeing 747 hit by lightning?

Over the years Boeing has delivered a total of 1,556 aircraft to major airlines all over the world. The aircraft is getting closer to retirement as the total aircraft in active service now number around 350.

The Boeing 747 is struck once or twice a year by lightning and given the global fleet in the world, this results in 350 to 700 lightning strikes per year.

   

Picture British Airways Boeing 747 during loading

Are there any incidents with a Boeing 747 caused by lightning strikes?

Picture of Qantas Boeing 747 lightning strike

Over the course of more than 50 years of service, there has been 1 crash attributed to a lightning strike. In 1976, an Iranian Boeing 747 freighter crashed due to the lightning strikes’ impact on its fuel tanks. The investigation carried out by the United States National Transportation Safety Board concluded that a bolt of lightning struck the fuselage near the cockpit and exited the left wing’s static discharger located at the wingtip. It created a spark in the fuel tank number 1, which contained 11,200 kg of fuel. The blast wave, at more than 5.5 bar, from the fuel vapor ignition caused the tank walls to collapse. It is most likely that the ignition spark penetrated the fuel tank due to an open circuit in a fuel valve wiring. With the explosion, the airflow deteriorated sharply, and the wings began to bend. As the flight was passing through an area of turbulence at high speed, the wing trim experienced mechanical stress. The entire left wing separated just a few seconds later.  

How many man-hours does it take to perform a lightning strike inspection on a Boeing 747?

After the aircraft is struck by lightning, the aircraft is grounded and thoroughly inspected for damage such as pits and burn marks by aircraft maintenance engineers to guarantee its airworthiness before the next flight. The inspection alone requires 3 licensed aircraft maintenance engineers and 12 hours to complete. The total man-hours for a Boeing 747 lightning strike inspection are 36 hours.

To assess the status of the aircraft, the aircraft maintenance engineers will move from station to station, from stringer to stringer, using additional equipment to inspect the top of the fuselage and the tail. The tail is 16 meters high and not easy to reach while the aircraft elevators and stabilizers are blocking the man lifter equipment. Often during the inspection, additional damage can be caused.

Picture of El Al Boeing 747-400 in hangar

How does a drone fit in the aircraft lightning strike inspection process of a Boeing 747?

Picture of KLM Boeing 747-400 in hangar

The use of drones for aircraft inspections brings game-changing results for the aviation industry and particularly Maintenance, Repair, and Overhaul (MRO) companies and organizations. All aspects of the inspection procedure, from drone flight to report generation, are automated, allowing the ground team to easily analyze and report the status of an aircraft.

In the event of a lightning strike, using a drone to perform aircraft inspection on the Boeing 747 can decrease the inspection time by 75%. A drone can speed up the entire process of the General Visual Inspection (GVI) during a lightning strike inspection, which can now be performed in minutes (60 minutes) instead of hours (12 hours). Our drone will safely fly around the aircraft and capture high-resolution pictures, allowing aircraft maintenance engineers to make a much faster damage assessment.

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747 lightning strike inspection