Cold War Era

The B-36 Peacemaker was so Huge that Catwalks were placed inside its Wings so that Mechanics could Maintain the Engines in Flight

Much was made of the fact that the wing of the B-36 Peacemaker was deep enough to allow engineers to enter it and maintain the engines in flight.


Conceived during 1941 in case Germany occupied Britain, when US bombers would then have insufficient range to retaliate, the B-36 Peacemaker was to be primarily a ‘10,000-mile bomber’ with heavy defensive armament, six engines and a performance that would prevent interception by fighters.

It was one of the first aircraft to use substantial amounts of magnesium in its structure, leading to the bomber’s ‘Magnesium Overcast’ nickname. It earned many superlatives due to the size and complexity of its structure, which used 27 miles of wiring, had a wingspan longer than the Wright brothers’ first flight, equivalent engine power to 400 cars, the same internal capacity as three five-room houses and 27,000 gallons of internal fuel – enough to propel a car around the world 18 times.

As explained by Peter E. Davies in his book B-36 ‘Peacemaker’ Units of the Cold War, much was made of the fact that the wing was deep enough to allow engineers to enter it and maintain the engines in flight.

One of the longest maintenance jobs was changing the numerous spark plugs (partly caused by the high lead content in the fuel), but this wasted time and was later reduced by using longer-lasting, platinum-tipped plugs. Alternators were also very unreliable in early B-36s, sometimes leaving aircraft in danger of suffering a total loss of electrical power. In flight, the engineer could work his way along the catwalk inside the wing to access each engine’s electrical panel if circuit breakers needed re-setting.

The wing’s depth at its root was 7.5 ft, allowing an engineer to enter and work inside it in flight. This became one of the B-36’s many sources of public amazement at its sheer size. In action, crew members hauled themselves along a crawl-way that passed over the wheel wells and above the inner engines in order to do limited in-flight engine monitoring and maintenance. At altitude, this meant wearing oxygen masks in these unpressurised spaces and surviving extremely low temperatures.

Pre-flighting the aircraft it included jobs for all the crew. Gunners could be called on to perform a range of difficult tasks, including assisting with manually lowering the main landing gear if it failed to drop down when activated in flight. After climbing out into the wing on a catwalk, a pair of crewmen (usually gunners) could access the open gear well through a zippered flap at its edge. From there, they could operate the down-lock mechanism by kicking downwards against it to make it lock manually at low altitude.

Pilot Lt Col Ed Sandin of the 5th SRW pioneered a hazardous technique for reaching down and inserting a main landing gear down-lock in flight after numerous attempts to make the gear lock down. The narrow crawl-way to this position over the wheel well meant that the job had to be done without wearing a parachute, while trying to avoid looking down into an open abyss below.

B-36 ‘Peacemaker’ Units of the Cold War is published by Osprey Publishing and is available to order here.

Photo credit: Lt. Col Frank F. Kleinwechter / U.S. Air Force

A Convair B-36 Peacemaker strategic bomber flying with number 3 propelled feathered
Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.

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