Chinese J-20 Seen Emitting Black Smoke at Zhuhai Airshow

China’s stealthy J-20 fighter jet was seen releasing black smoke at the ongoing Zhuhai Airshow (Nov.8-13), which experts believe, could be because of Auxiliary Power Unit or some problem with the engine.

The fifth Generation fighter was displayed to the public for the first time at the show. The J-20 landed, taxied and parked before the public for a closer view. It led to some close-up photographs being clicked, showing its brake parachute, part of the cockpit, and the enclosed air-to-air refueling probe. The fine workmanship and finishing of the J-20’s body were also visible, baring the highly sophisticated metallurgical, forging, and precision cutting processes.

A video circulating on social media showed a puff of black smoke being released from a small exhaust in the bottom spine of the plane, just before the tails (vertical stabilizer) section.

Some onlookers claimed it was an issue with the aircraft’s engines, which China has still not succeeded in fully mastering. Few other experts said it was the Auxiliary Power Unit (APU), which also operates the same way on the American F-22 Raptor.

“That’s (emitting black smoke) a most common feature when the APU starts,” Chinese military expert Andreas Rupprecht was quoted as saying by EurAsian Times.

The APU is usually a miniature jet whose primary role is to drive the main engine to complete the start-up operation.

It also provides part of the power and high-pressure air or fluid when the main engine is turned off to save fuel and reduce its wear and tear. This cumulatively has a significant positive impact on the main engine’s life and maintainability.

On analyzing construction numbers on J-20 (“CB0369″ and “CB0370”) and J-16 (“1105″) jets displayed at the event, Rupprecht told Defense News that the People's Liberation Army Air Force (PLAAF) has at least 200 J-20s and more than 240 J-16 multirole strike aircraft currently in service. There have been four production batches of the J-20 and 11 b­atches of J-16s.

Rupprecht has authored several books on China’s military aviation industry as well as on PLAAF.

J-20s on static display at the air show are powered by indigenous WS-10C engines and features low-observable sawtooth edges on their afterburner nozzles.

Rupprecht’s estimate is somewhat consistent with that of Chinese experts’ who put the number as between 250-300.

Chen Liu, a delegate to the 20th CPC National Congress from the PLA and the Armed Police Force, was quoted as saying by state media at an October 2022 event in Beijing that the J-20 “is now active in all five theater commands across the country.”