One of two nose wheels on the Sydney-bound Boeing 737 fell off as the plane was preparing for takeoff from Melbourne airport on Saturday.
The Australian Aircraft Engineers' Association says the problem could have been picked up if Virgin inspected its planes before each flight.
But chief executive Brett Godfrey says it is unlikely the problem would have been noticed.
A Virgin Blue spokesperson says an initial review with Boeing showed that similar incidents had occurred with other airlines.
Virgin Blue, Boeing and the Australian Transport Safety Bureau have launched an investigation into the incident.
Aircraft Engineers' Association secretary Steve Purvinas called on Virgin Blue to conduct pre-flight safety checks before all flights.
"In this case we were lucky that the failure occurred on the ground - the release of the wheel assembly in-flight could have seen a loss of aircraft," he said.
Funds sought from shareholders
Meanwhile, Virgin Blue wants to raise more than $A231 million from shareholders to strengthen its balance sheet as it forecast an annual loss and Mr Godfrey announced he will step down.
Investors will be offered shares at 20 cents each, a discount of a third on the airline's closing price on Friday.
Virgin Blue expects a loss of up to $A165 million for the June year, and says it will break even in 2010.