through an opening 13 in wall 11 that is on the opposite side of that wall from the engine core side thereof flange 12 is part of a metal container 14 for heat exchanger 10 provided on the engine core side of wall 11 a further bracket 15 located primarily on the airstream side of wall 11 and fastened to container 14 through opening 13 holds that container against wall 11 bracket 15 has triangular shaped sidewalls across from one another with an opening therebetween to the interior of container 14 below that bracket on the upstream side of opening 13 on the left in fig1 i e the front side of heat exchanger 10 two further triangular shaped sidewalls are provided in bracket 15 across from one another with an opening therebetween to the interior of container 14 below on the downstream side of opening 13 on the right in fig1 these two openings in bracket 15 permit a portion of the fan airstream to enter into the interior of container 14 on the upstream side and to exit from container 14 on the downstream side thereof whenever the deployable portion of heat exchanger 10 is at least partly deployed in the engine fan airstream through an opening 13 the triangular shaped sidewalls on the upstream side help guide that portion of the airstream into the interior of container 14 whenever the deployable portion of heat exchanger 10 is at least partly deployed in the engine fan airstream by limiting to an extent airflow.