You must have heard the name of the JF-17 fighter aircraft, which was made jointly by China and Pakistan. It is often compared to the Tejas aircraft made in India.
According to the report of Daily Sun Newspaper, Pakistan Air Force’s most important aircraft is faltering over the faulty engine. It is not standing up to the big claims made by China.

It is believed that in today’s date, it has become a liability for Pakistan. The PAC JF-17 Thunder is a lightweight, single-engine fourth-generation multi-role combat aircraft jointly developed by Pakistan Aeronautical Complex (PAC) and Chengdu Aircraft Corporation (CAC). Designed by Pakistan and developed by both China and Pakistan, the JF-17 was said to replace the Mirage III and Mirage V combat aircraft completely.
Since it is a multi-role combat aircraft, it was believed to be used for different things such as interception, ground attack, anti-ship, and aerial reconnaissance.

JF-17 was designed in 1999. China started its production in 2007. And production in Pakistan began in 2008. So far, Pakistan and China together have made 132 JF-17 aircraft.

What shortcomings have come to the fore in this Aircraft?

For starters, there are many cracks in the engines. The serviceability condition is also deplorable, and maintenance is very high. Performance is deteriorating rapidly of this aircraft. Cracks can be seen in the strake areas of the aircraft. Strake is responsible for how aircraft operate with gravity.

One other issue is that the JF-17 emits black smoke during flight.
JF-17’s Rd 93 Aero engines which China had procured from Russia.
Russia warned that the engine is faulty and we would never use it. Despite the warning, China used this engine in JF-17, and as expected, it caused trouble. Emitting smoke while flying is a huge issue that makes the aircraft vulnerable in combat.

Islamabad has repeatedly complained to Beijing about this and said we want this particular engine to be replaced. Then China asked Russia to replace it, but Russia refused. Then China thought of making its alternative which would be used in JF-17.
And this alternative engine, Guizhou WS-13 Taishan, is under development for a long time.

Due to the high fuel consumption of JF17, it will require air to air refueling for a long flight, but the provision of air to air refueling is not available in this aircraft.

One of the biggest issues is that Pakistan is entirely dependent on China and other countries for the spare parts of this aircraft.

Due to these issues with JF-17, Pakistan neither displays the JF 17 in Major air shows nor allows it to participate in any exercise. And Pakistan is forced to ground 40 percent of its JF-17s.