Along the winding drive through the 300-acre compound of Long Island’s only veterans’ medical center, banners line the road stating the presumed values of the institution: integrity, commitment, advocacy, respect and excellence.

But in recent months, a series of troubling failings and allegations of wrongdoing have called into question the care being provided to thousands of the nation’s military personnel by the Northport Veterans Affairs Medical Center, in Northport, N.Y., with charges of abuse that include widespread billing fraud and the failure to report the death of a patient for months after his body was found in a building on the complex.

The problems plaguing the medical center first drew attention after all five of the hospital’s operating rooms were shut down in mid-February, because sand-grain-size black particles had begun falling from the air ducts. Veterans in need of surgery had to go to other hospitals for care, often leading to further delays in their treatment or postponed operations.

The closing of the operating rooms was first reported by The New York Times in May. Representative Lee M. Zeldin, a Republican who represents the First District on Long Island and is a member of the House Veterans’ Affairs Committee, then collected information from whistle-blowers and others and turned it over to the committee, which will hold a public hearing at the medical center on Tuesday.