LOS ANGELES (AP) — Barron Hilton, a hotel magnate who expanded his father's chain and became a founding owner in the American Football League, died Thursday at his Los Angeles home. He was 91. Hilton's family said he died of natural causes. He transformed Hilton into the industry's top brand during his 30 years as its chief executive. The Blackstone Group bought the international chain's 2,800 hotels — including its famed Waldorf-Astoria — for $26 billion in 2007. "The Hilton family mourns the loss of a remarkable man," said Steven M. Hilton, his son and chairman of the Conrad N. Hilton Foundation, said in a statement. "He lived a life of great adventure and exceptional accomplishment." An avid pilot who served as a Navy photographer during World War II, Hilton didn't begin working for his father's company until 1951, after he'd made his own fortune in orange juice products, an oil company and an aircraft-leasing business. Hilton also founded the Los Angeles Chargers in the AFL and oversaw the AFL-NFL merger. William Barron Hilton was born in Dallas in 1927 to Conrad N. Hilton, the founder of Hilton Hotels, and Mary Adelaide Barron. Hilton challenged his father's will — arguing the foundation's shares of Conrad Hilton's fortune that were being used to help Catholic nuns could leave the company open to a hostile takeover— in 10-year legal battle that ended in a settlement. "It was a very painful decade," Hilton told USA Today in 1995. "Hilton vs. the nuns was not the best public relations move." Hilton's wife, Marilyn Hawley Hilton, died in 2004. He is survived by eight children, 15 grandchildren — among whom are famed heiresses Paris Hilton and Nicky Hilton — and four great-grandchildren. Hilton was the chairman emeritus of Conrad N. Hilton Foundation. He left about 97% of his estate to the foundation, which expects the donation to grow its endowment from $2.9 billion to $6.3 billion.