Prince William is to undergo a raft of secret cancer checks after it was revealed his former military flying instructor had died aged just 47, sources have sensationally claimed.

The future king flew the same toxic fume-belching choppers during his flying career and Buckingham Palace aids are desperate to avoid a triple whammy of cancer cases in senior royals, RadarOnline.com can reveal.

The intelligence comes as William’s wife Kate Middleton and dad King Charles have both been fighting killer cancer, with the Princess of Wales recently revealing she was in remission.

A palace inside told us: “William will undergo a range of tests to make sure he’s not suffering from any illnesses connected to his military service. Heaven forbid that he’s developed any form of cancer in the service of his country.

“The Royal Family does not need a triple whammy of cancer-stricken senior royals on its books given Charles and Kate have both been battling the illness over the last months,” our insider said.

“It is a very worrying time to say the least.”

Wills’ instructor died of cancer after years of exposure to toxic helicopter exhaust fumes sparking legal action against top brass.

Flight Sergeant Zach Stubbings passed after over a decade of battling multiple myeloma, cancer of the blood and bone marrow, RadarOnline.com revealed this week.

The prince, 42, regularly flew Sea King helicopters , the same aircraft as Stubbings.

Dad-of-three Stubbings was diagnosed in 2013, thirteen years after joining the RAF Search and Rescue.

He trained Prince William when he was based at RAF Valley in Anglesey in the United Kingdom from 2010 to 2013.

His passing was announced by Richard Sutton, a former Navy Commander and pilot who was also diagnosed with cancer 12 years ago.

Prince William has been pictured flying Sea King helicopters in the early 2010s.

Stubbings previously told how he was often surrounded by black exhaust fumes.

In an interview last year, he added: “If you’re by the cargo door, the exhaust comes right through.

“Even worse, if you’re working on the winch, which I was, you’re putting your head right out into it.

“We had to clean everything. It didn’t feel right. There was no protection, nothing. We all complained about it.”

He said how he would often get “a face full” of the sooty fumes, noting the dreadful smell.

Sufferers are now set to sue the British military for millions in compensation, we revealed.

The UK government is investigating how many military personnel have been diagnosed with cancer, after claims that some helicopters left crew exposed to toxic fumes.

At least six cases have already been settled out of court by the Ministry of Defene (MoD), with dozens of other aircrew and families understood to be in the process of suing.

They claim that officials knew about safety concerns with certain aircraft as far back as 1999, but chose not to tell the crew or introduce sufficient safety precautions.

The MoD says it takes “the health of our personnel extremely seriously” and is currently testing the exhaust emissions of some military helicopters.

Diseases contracted by some of the crew who flew the helicopters include lung cancer, throat cancer, testicular cancer and some rare forms of blood cancer.