There have been several questions and comments from the readers on this website about why Erickson Aero Tanker’s MD-87 air tankers drop retardant with the landing gear down. The most commonly accepted explanation was to reduce airspeed, especially when making a downhill drop. This was why some older air tankers, like the DC-7 according to “Johnny”, kept the gear down.
But Erickson’s MD-87’s are required by the FAA to lower the gear while dropping — in fact it is specified in their Supplemental Type Certificate (STC) issued by the FAA. The reason is the prevention of stalling.
Earlier this year Ericson petitioned the FAA for an exemption from this requirement, and requested a “Flaps 40/Landing Gear Up” configuration while dropping, but on June 28, 2017 that exemption was denied.
Below is an excerpt from the decision which was signed by Michael Kaszycki of the FAA’s Aircraft Certification Service:
I deny Erickson Aero Tanker, LLC’s, petition for an exemption from 14 CFR 25.201(b)(1), that would have allowed aerial firefighting retardant drops in a configuration that does not fully meet the stall characteristics requirements on the modified DC-9-87 (MD-87) airplanes.