1
$\begingroup$

Piper Seminole (PA-44-180) VLO (max gear retraction speed) is 109 KIAS. I've heard that manufacturer published limitations are significantly lower than actual structural and system limitations. What are the potential repercussions of retracting gear at 10, 20, 30 KIAS over VLO?

$\endgroup$
  • $\begingroup$ VLO is the maximum gear extended speed, not retraction. Is that what you mean? $\endgroup$ – Ron Beyer Sep 25 at 19:37
  • $\begingroup$ I think he just means forgetting to retract on climbout and finding himself too fast with the gear still down. $\endgroup$ – John K Sep 25 at 20:13
  • 1
    $\begingroup$ No. VLO is what I meant - the maximum speed at which the gear may be operated. In the case of the Seminole, that’s 109 KIAS. The maximum extend speed is 140 KIAS and that’s VLE. Hope this makes sense. $\endgroup$ – Alexander G Sep 25 at 20:31
5
$\begingroup$

The gear itself and its attachments being pretty beefy, you can't really damage the gear legs extending them at any speed the airplane can fly at.

The limitations usually relate to the doors, which are more delicate, and having large surface area, are far more affected by air loads. So the main effect of exceeding a gear speed limitation is the risk of bending or distorting, or in extreme cases blowing off, gear doors.

If you have a minor exceedance of 10kt, I'd just give a visual check of the doors later. If it was a major exceedance of 20kt or more a tech should look at it. The doors may look ok at a glance, but if they are deformed they can prevent the gear from extending next time, if, say a distorted door's edge overlaps the opening and slips past on retraction but hangs up on extension.

Extension/retraction speeds, VLO, or speed you can operate the gear selector, and maximum operating speed with the gear down, VLE, or speed you can fly with the gear down and locked, are sometimes different (VLO is normally lower than VLE if they are) because there is a limit speed that affects the gear while in transit, whereas once down and locked you can speed up. This can be from sequenced gear doors that are only open during the extension/retraction cycle, or a limitation on the ability of the hydraulic system to retract, say, a forward retracting nose gear against air loads (a speed limitation could also be related to a stability and control issue as well).

I dimly recall from my multi training days (but not totally sure) that the limitation on the Seminole was related to its rather weak hydraulic pump which had to work too hard above a certain speed, stalling the pump or popping the CB, something like that. Some amount of safety margin would have been applied to the speed the problem was happening at, giving the published limitation of 109.

$\endgroup$
  • $\begingroup$ Thank you so much for this. It makes perfect sense for the extend limitation. But what about the retract limitation of 109? The POH says you shouldn’t retract the gear above 109 KIAS. $\endgroup$ – Alexander G Sep 25 at 20:33
  • $\begingroup$ I added some extra context. $\endgroup$ – John K Sep 25 at 21:42
  • $\begingroup$ Thanks so much! The clarification on the Seminole was exactly what I was seeking. I, unfortunately, busted my Multi Comm ride today because I retracted at 113 vs 109 after recovering from an emergency descent. Live and learn. $\endgroup$ – Alexander G Sep 25 at 22:57
  • $\begingroup$ I blew my initial IFR ride and had to redo part of it. If you aren't using a home computer sim to practice and drill your training at home, you should be. $\endgroup$ – John K Sep 25 at 23:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.