Rolls-Royce Corp. in Indianapolis is fighting a touchy gender discrimination lawsuit by two high-level female managers who paint an unflattering picture of working in the jet engine maker’s male-dominated culture.

In their federal lawsuit, Sally Randall and Rona Pepmeier say they have been paid less than their male counterparts, passed over for promotions and witnessed male executives putting down women.

The two refer to a corporate “code of silence” at Rolls-Royce that inhibits women from talking about being underpaid or not promoted, out of fear they will be fired if they do.

Randall, 59, and Pepmeier, 36, say they have been removed from bonus plans they previously were eligible for and no longer are on a career track for promotions since they filed their lawsuit three years ago.

Judge Jane Magnus-Stinson, who presides over the case in federal court in Indianapolis, has been asked to declare the lawsuit a class action, which would allow up to 537 female engineers and managers at the Indianapolis facility to join as plaintiffs.

If the class is approved, claims easily could run into the millions of dollars against Rolls-Royce, based on several years’ worth of alleged underpayments to its female engineers and managers. The case involves only white- collar female employees at certain pay grades at Rolls-Royce’s Indianapolis facility, which formerly was Allison Engine Co.

Rolls-Royce won’t discuss the lawsuit in public, citing its policy of not commenting on pending litigation, said a spokeswoman.

In its latest filing this week, Rolls-Royce calls the gender discrimination charge “absurd,” contending the company doesn’t discriminate against women and actually promotes them faster than men. It criticizes as “fundamentally flawed” the findings of the plaintiffs’ statistical expert, who found Rolls-Royce paid female engineers and managers 4 percent to 6 percent less than comparable men from 2004 to 2007 after adjusting for factors such as experience.

Pepmeier and Randall said they filed their lawsuit reluctantly after trying internally to get the company to deal with their allegations.

“I started digging and found out through word of mouth . . . that my (male) peers were doing much better than I was from a financial standpoint,” said Pepmeier, who joined Rolls-Royce in 1998. She is a senior manager of process excellence and works in the company quality program.

“It just seemed I couldn’t change it through the company, and I had to go outside,” said Pepmeier, who holds a master’s degree in industrial engineering.

Randall, a subsystem manager who holds a master’s in thermal science, said she first questioned her treatment about 10 years ago when she saw a salary survey showing her pay was 20 percent lower than the average for mechanical engineers with her experience.

When she threatened to leave over the issue, she said the company gave her a 20 percent raise, but she said it made her think, “If I was worth this, why didn’t you pay me this all along?”

The two women separately contacted the Indianapolis law firm of Betz&Associates, which put their claims into one lawsuit. “They’re taking an enormous (career) risk doing this,” said Sandra Blevins, their main attorney.

Pepmeier, who worked in her father’s sheet metal shop growing up in western Pennsylvania, said her career suffered after she began questioning her pay and lack of promotions. Her salary and bonus rose from $151,444 in 2004 to $307,036 in 2006, but her 2007 salary was $130,170 with no bonus listed, according to an affidavit by a Rolls-Royce human resources specialist that was filed in court.

“Discrimination has gotten a lot more subtle” by employers and often can be shown only through sophisticated pay studies, said Roberta Steele, a partner at Goldstein Demchak Baller Borgen&Dardarian in Oakland, Calif.

The plaintiffs’ expert is Richard Drogin, a partner in a California statistical consulting company who has been an expert witness in more than 250 court cases. Rolls-Royce has retained Bernard Siskin, who works in Philadelphia for another California consulting company and has 40 years of experience in statistics.

Passage of the Lilly Ledbetter Fair Pay Act by Congress, the first bill signed by President Barack Obama on taking office, is expected to aid plaintiffs in the case by making it easier to figure their potential monetary claims.