* Q2 net loss 423 mln euros vs profit of 47 mln year ago
* CEO says will resolutely face necessary changes
* 2015 EBITA seen at 150-170 mln euros vs 262 mln year ago
* Shares down 1.2 percent (Adds details on industrial unit, charges, analyst comment, shares)
By Georgina Prodhan
FRANKFURT, Aug 12 (Reuters) - The new chief executive of Germany's Bilfinger said he would do whatever it took to turn the company around as problems escalated at its main division servicing oil and gas clients and charges for a business it is selling pushed it to a record net loss.
The engineering and services group predicted a drop of as much as 43 percent in its full-year core earnings after an unexpectedly sharp drop in oil prices hit its Industrial business, compounding problems at the up-for-sale Power division.
Industrial, which now accounts for the majority of Bilfinger's business, on Wednesday reported an 11 percent fall in core profit in the second quarter.
"The negative impact from the low oil price on those divisions that are active in the oil and gas sector has... been significantly stronger than initially anticipated," Bilfinger said in its quarterly earnings report.
CEO Per Utnegaard said: "We will resolutely face the changes that are necessary: We will increase our profitability, reduce complexity in the group, simplify processes and decrease costs in all areas."
Utnegaard, brought in by major shareholder and activist investor Cevian after Bilfinger issued six profit warnings in the space of a year, is conducting a review of Bilfinger's businesses and is due to present the results in October.
Bilfinger's Power business has suffered from Germany's switch to renewable energy, which has left major customers such as large German fossil-power providers unable to invest or renew maintenance contracts.
Charges of 430 million euros ($476 million), including a 330 million writedown of the Power division and 30 million in restructuring costs for Industrial, pushed Bilfinger to a 423 million euro net loss from a profit of 47 million a year ago.
Bilfinger said it aimed to sell the power business, which accounted for about a fifth of group output with 1.45 billion euros in 2014, by the middle of next year.
The company now expects full-year adjusted earnings before interest, tax and amortisation (EBITA) of between 150 and 170 million euros, down from 262 million in 2014, and output similar to last year's 6.25 billion euros.
Second-quarter adjusted core profit fell 5 percent to 53 million euros, in line with the company's guidance, output rose 7 percent and orders jumped 48 percent on the extension of major service agreements with long-standing customers.
"We like the operational improvement," wrote DZ Bank analyst Jasko Terzic, who rates Bilfinger "buy".
But Terzic also noted that the one-off charges were higher than expected. "The operational turnaround needs notably higher efforts than we have expected so far."
Shares in Bilfinger were down 1.2 percent to 37.74 euros by 0806 GMT, outperforming the German mid-cap index, which was down 2.7 percent. ($1 = 0.9029 euros) (Editing by Maria Sheahan and Jane Merriman)