A clipboard left in an engine cowling during pre-flight checks was "ingested" into a Jetstar Airbus A320 before it took off from Auckland bound for Sydney, with the plane later forced to return to New Zealand.

The worker was inspecting the aircraft at Auckland Airport when he placed a clipboard containing paperwork inside one of the engines to protect it from the rain and wind — and then forgot all about it.

The plane was scheduled to fly between Auckland and Sydney on October 27 when the incident occurred. It was already in the air by the time the captain was alerted to the situation by an Auckland air traffic controller, according to an Australian Transport Safety Bureau (ATSB) report.

"While preparing the aircraft for departure the leading hand placed a clipboard in the right engine which was subsequently ingested during start-up," the ATSB report found.

"During the (subsequent) walk-around the dispatcher noticed the clipboard in the right engine but, believing it would be retrieved prior to the aircraft departing, the dispatcher did not notify the leading hand or supervisor of the foreign object debris as per company procedures."

The captain was notified there was a problem after debris - the remains of the clipboard - was found on the runway after the plane had taken off.

Once notified, the captain scrambled, first checking the plane's engine instruments and finding no abnormal indications. He then pressed flight control for more information, and was informed the clipboard had been placed in the inlet and that paper debris had been found on the tarmac.

The next step was to contact the company's engineer at the airport, to find out if is was just paperwork or a clipboard containing a metal clip, and was told that a piece of sheared metal had been found.

Uncertain what damage had been done to the engine he decided to return to Auckland.

The aircraft was inspected and paper was found throughout the engine.

Minor damage was found to an engine fan blade and attrition liner, a part used to dampen noise that's located on the inside of the engine.

The ATSB warned of the seriousness of such a situation, staying: "The presence of foreign object debris poses a significant threat to aircraft safety. It has the potential to cause aircraft damage during critical phases of flight, costing airlines and airports millions of dollars each year.

"This incident demonstrates the effect foreign object debris has on aircraft operations and emphasises the importance of not placing objects in aircraft engines. It further highlights that all staff operating near aircraft are responsible for reporting any non-normal events they encounter.

"It should not be assumed that others will perform a task where a hazard has been identified."

The report also detailed how the captain faced several obstacles in trying to piece together exactly what was going on.

"The captain stated that, to obtain more information about the incident, numerous calls were made to other agencies, which took considerable time. Further, due to poor communications, he was unable to contact the operator's maintenance controller to discuss the engine's status."

A Jetstar spokesperson told news.com.au its safety procedures have been updated following the incident.

"A plastic clipboard was inadvertently left on the engine cowl of a Jetstar A320 aircraft by our ground handler at Auckland Airport just prior to departure," the spokesperson said.

"While this incident didn't impact the safe operation of the aircraft, we take it very seriously. Since this occurred we have updated our procedures which includes a specific warning about not placing items in the engine cowling and improved detail around checks and responsibilities of the aircraft dispatch process."