A safety advisory has been issued by the Civil Aviation Administration of China (CAAC) that is urging operators of second-generation of 737 Classic Series (-300, -400, -500) aircraft to check the main landing gear of their jets. The advisory was triggered by the discovery of cracks on two aging 737s.China Postal 737

Main landing gear cracks discovered

According to FlightGlobal, the CAAC has issued a safety bulletin that prompts operators of Boeing 737-300/400/500 aircraft to check their main landing gear. The notice is due to the discovery of cracks "between the fastener holes of the main landing gear’s upper rear beam" on two 737s. The operator of these aircraft was not disclosed.

CAAC information shows that the two aircraft had reached 4,600 and 2,900 flight cycles, respectively- significantly lower than the 15,000 flight cycle inspection interval that is in place by the civil aviation body. Therefore, any operators in China still operating the type have been encouraged to inspect their aircraft as soon as possible, regardless of proximity to the 15,000 flight cycle milestone.

The advisory also prompts airlines to check for fuel leakage near the main landing gear during line maintenance. Structural fatigue management measures should then be implemented during checks and if any structural damage or defects are discovered during maintenance, they should be reported to the CAAC.

The 737 Classic Series

Data from Planespotters.net shows that about 650 737s of this generation are still listed as active. Cirium fleets data reported by FlightGlobal shows that there are 68 737 Classics in service in China. In China, and throughout much of the world, many of the jets are used as cargo aircraft while a handful are operated by governments as military jets. China's People’s Liberation Army Air Force, the Indonesian Air Force, and South Korea's Air Force all operate 737 Classic aircraft.

On the other side of the planet, the Air Forces of Chile and Mexico also operate these old jets.

Interestingly, the King of Thailand has a fleet of four 737s. Two are -400s while the other two are the newer -800.

737 Yangtze river express
While many 737 Classic jets have been retired due to their age, operators around the world still operate the type, with data showing that hundreds are still active - mostly as freighters. Photo: Maarten Visser via Wikimedia Commons

The Boeing 737 Classic is becoming an increasingly rare sight these days, with many airlines retiring the type. This is a process that has predated the current global crisis. Indeed, with the production of the classic 737s ending in 2000, the youngest models would now be 20 years of age.

However, the events of 2020 have sped up the retirement of some aircraft. For example, European carrier airBaltic returned from its flight suspension, having waved goodbye to its final Boeing 737 Classic aircraft. More recently, we also reported on the last flight of an ANA Boeing 737-500.

How long do you think this series of aircraft will continue to fly? Even if aircraft are well-maintained, is there an age limit that should be imposed?  Let us know your thoughts in the comments.