Cobham has been struggling to get back on track after incurring very large debts on takeovers.
It needed a £500 million rights issue when it ran into trouble on a USAF contract.
Cobham CEO David Lockwood called the offer an “endorsement of the turnaround strategy” he has been implementing for the last two and a half years.
“These fundamentals, along with the investment in the business Advent can provide, will enable us to leverage the quality of our products and services,” said Lockwood.
Cobham chairman Jamie Pike said the offer “represents an opportunity for shareholders to realise their investment in Cobham in cash in the near term”.
Cobham employs 10,000 people.