UPDATE 2-Rolls-Royce agrees to early inspection of problematic Trent engines

* Early inspections after Singapore Airlines grounds jets

* Engine has had a problematic entry into service

* New blades being tested, expected in use from 2020

* Stock underperforms bluechip index (Adds analyst comment, details, shares)

By Noor Zainab Hussain

April 10 (Reuters) - Rolls-Royce has agreed to an early inspection of some Trent 1000 TEN engines by regulatory authorities, a week after Singapore Airlines Ltd grounded two Boeing Co 787-10 jets fitted with the units.

The latest version of the Trent engine has been dogged by problems since entering service at the end of 2017. According to Rolls-Royce, by late February 35 787s had been grounded globally due to engine blades corroding or cracking prematurely.

"This blade deterioration is a known issue but it is occurring faster than we expected on some engines," Chris Cholerton, Rolls-Royce President for Civil Aerospace, said on Wednesday.

The accelerated inspection regime will allow Rolls-Royce to confirm the health of the more than 180 engines in service over the next few months.

Shares in Rolls-Royce were trading down 0.5 percent by 0751 GMT, underperforming the wider FTSE 100 index.

Singapore Airlines grounded its two jets last week after engine checks showed premature blade deterioration.

Jefferies analysts said the affected engines were being operated on routes to Japan, Korea and Thailand, meaning they had a relatively high take-off and landing cycle.

In February, Rolls-Royce allocated another 100 million pounds to fix the engine problems and raised a related accounting charge to 790 million pounds ($1.03 billion) from 554 million pounds six months earlier, contributing to a full-year operating loss of 1.16 billion pounds.

However, on Wednesday, the company reiterated its current guidance for in-service cash costs on the Trent 1000 in 2019 and 2020.

Rolls-Royce engineers have been developing and testing an enhanced version of the engine blades, which the company said it expects to start incorporating in the engines early next year.

The company said an airworthiness directive would be issued by the European Aviation Safety Agency.

Rolls-Royce, which makes engines for large civil aircraft and military planes, is keen to avoid further problems with its Trent 1000 engine and last month dropped out of the race to power Boeing's planned mid-market aircraft. ($1 = 0.7652 pounds) (Reporting by Noor Zainab Hussain in Bengaluru; Editing by Arun Koyyur and Kirsten Donovan)