He went on because there was really nothing to turn back for.
His dull apathy of despair received something in the nature of a shock when he walked around the corner and almost butted into Bland, who had just finished tightening a turnbuckle and stepped back to walk around the end of a wing.

Bland's pale, unpleasant eyes watered with welcome--which was even more surprising to Johnny than his actual presence there.
"Why, hello, old top! They told me you'd be let out t'day, but I didn't know just when.

You're looking peaked.

Didn't they feed yuh good ?" Johnny did not answer.

He went up and ran his fingers caressingly along the polished propeller blade that slanted toward him; he fingered the cables and touched the smooth curve of the wing as if he needed more evidence than his eyes could furnish that the Thunder Bird was there, where he had not dared hope he would find it.