Mr Spaceman From Canada, joined Mar 2001, 2780 posts, RR: 15 Posted (10 years 4 months 4 days 13 hours ago) and read 4000 times:
Several days ago, an Air Canada JAZZ Dash-8-300 was experiencing problems while on approach to Toronto Intl (YYZ) from Windsor, Ontario (YQG). This JAZZ Dash-8's FLT # was 7740.
Shortly after checking in with Toronto's arrival controller, the pilot began explaining that he had a caution light flickering (he never said for what system), and that his company's maintenance wanted him to do an "Alternet Extension".
He explained to the controller that this meant he required a 10 mile final and needed to maintain 130 knots on his approach (arriving airliners at YYZ normally fly their approaches at 170 or 190 knots once on the ILS).
He also advised the controller that once his gear was extended, he wouldn't be able to Go Around! I suspect he was asking the controller to make sure no aircraft were on the runway (unless they were ready to roll with NO DELAY).
He was then handed over to the tower...and I lost his next transmissions.
Does anyone feel like guessing what this Dash-8-300's problem was?
If so...Why would a Dash-8 not be able to overshoot and go around if nessesary?
Also, what abnormal or emergency checklist items would dictate that he had to maintain 130 knots on a 10 mile approach and then have only ONE shot at landing?
Beefmoney From United States of America, joined Oct 2000, 1111 posts, RR: 4 Reply 1, posted (10 years 4 months 4 days 12 hours ago) and read 3945 times:
This was probably a problem with the flaps or gear. Alternate extention procedures do not allow the flaps or gear to be retrated once they are placed in the landing configuration. If this was a problem with the flaps, and they extended them using the alternate method, and they needed to go around on landing, the flaps would severely limit their ability to do a safe go-around. Probably the same in the case of a gear problem. They just wanted to make sure they didnt have to go-around, because if they did go around it may cause some major problems.
Disclaimer: I am not a Dash-8 pilot. I have no first hand experience with the Dash-8. I am only using my time in the Cessna 152/172 to answer the question.
Mr Spaceman From Canada, joined Mar 2001, 2780 posts, RR: 15 Reply 2, posted (10 years 4 months 4 days 11 hours ago) and read 3916 times:
Thanks for your reply.
It sounds like you've learned a lot about "Alternate Extension" procedures (hopefully not by first hand experience). This pilot's problem was the first time I'd ever heard of the phrase. He even took the liberty of explaining what it meant to the controller. Although, that was probably so the controller new how it would effect this particular aircraft's performance.
I thought the problem was likely the landing gear, but, couldn't figure out why a Dash-8 wouldn't be able to climb with the gear down?
I didn't even think about the flaps for some reason. I figured it could be many things gone wrong.
I woner why this pilot didn't explain what the flickering caution light was for?
I've heard other pilots request "the trucks" when their gear needed to be lowered manually. I heard a pilot this week ask for a lower altitude because his cabine pressure was "messing around". Today a pilot of a Beech 1900 requested a shallow approach because his left engine was out. (all these aircraft were turboprops!).
Questions...I suspect the longer approach was asked for to give the pilots more time to troubleshoot what was wrong, but, why do you think they needed to maintain only 130 knots? Also, what speed does a Dash-8 land at for a normal approach? (ballpark figure).
Scootertrash From United States of America, joined Aug 2001, 569 posts, RR: 10 Reply 3, posted (10 years 4 months 4 days 10 hours ago) and read 3868 times:
I'm a Dash 8 driver, so lemme take a stab at it...
The only reason why I can think that the above occured was that the crew observed a flickering "Landing Gear Inop" caution light. This light does not mean that the landing gear will not come down or will fail upon touchdown, it simply means that one of several hydraulic valves which control the landing gear and doors is out of position. Thus, if the landing gear were to be lowered by the normal hydraulic means, the landing gear doors may be damaged as they may not move out of the way of the landing gear itself.
The checklist for this caution light dictates that the crew slow to 140 knots (cannot fly with the gear doors open above 140 knots), then to lower the gear by the alternate means, which is basically by pulling two cords, one for the main gear and one for the nose gear. The cords have two detents; the first releases the gear doors and the second releases the gear uplocks, allowing the gear to drop into position.
As for this pilot's requests: The 10 mile final was probably asked for so that the crew could have plenty of time to run the checklist, which is kinda long. The speed (130 knots) was probably as fast as the pilot felt he wanted to go with all his doors hanging in the breeze. AC Jazz procedures may require this speed as well, every airline can be a little different. As for the pilot's comment about being unable to go around, this is not entirely accurate and you are probably taking him a tad out of context. Once the landing gear are lowered by alternate means with a "landing gear inop" caution light, it is highly improbable that the gear would be able to be retracted on go-around. While the Dash-8 will climb very well with two engines and the gear down, on one engine with a heavy load, this climb performance could be quite poor indeed. Thus, as luck is always provided in small amounts in the flying biz, the prudent pilot will inform ATC of his inability to go-around due to traffic. So the translation of that remark is: "keep everyone the hell out of my way 'cause my airplane is broke."
Sorry for the long post... hope that answers all of your questions.
Mr Spaceman From Canada, joined Mar 2001, 2780 posts, RR: 15 Reply 5, posted (10 years 4 months 3 days 16 hours ago) and read 3651 times:
> Scootertrash, Thanks for your reply. That was great information.
As a Dash-8 driver yourself....Have you ever had to lower your DHC-8's landing gear by using the alternate means? (pulling the 2 cords).
Also, when shooting an approach in your Dash-8 to an airport with runways as long as Toronto's, and on a standard atmospher day (+15C) with an average load...what would be a usual target speed for crossing the threshold?
Finally, in the Dash-8 cockpit photos below, can you see these 2 sets of cords for extending the landing gear manually, or are they located out of view? (Ex: under an access panel in the floor between the pilot's seats).
Scootertrash From United States of America, joined Aug 2001, 569 posts, RR: 10 Reply 6, posted (10 years 4 months 3 days 5 hours ago) and read 3534 times:
Thanks for the complement Chris.
As for your questions... Nope, I have never had to lower the landing gear using the "lawnmower cords." I have, however, had to lower the gear using the other alternate means: The Power Transfer Unit (PTU). The landing gear on the Dash is powered by the #2 (right side) hydraulic system. If for some reason you lose hydraulic pressure on the #2 side, the PTU will use the pressure from the #1 side to spin a special pump. This pump then drives the fluid on the #2 side, providing adequate pressure to lower the gear. On the Dash, the PTU can raise or lower the landing gear.
The cords we have been talking about are used in two situations: If the "Landing Gear INOP" caution light illuminates or if there is a loss of hyraulic fluid, not just pressure, on the #2 side. You cannot see those cords in the pictures above. The cord for the main gear is located above the FO's head behind a door. The cord for the nose gear, along with the alternate landing gear position indicators, is located behind a door on the floor just to the left of the FO's seat.
As far as speed crossing the threshold go... it depends a great deal on the weight and whether we are talking about a 100, 200 or 300 series. In a -100, I can cross the Threshold as slow as 87 knots with a light airplane and the flaps at 35 degress. Typical for all models is about 100 to 120 knots.
Mr Spaceman From Canada, joined Mar 2001, 2780 posts, RR: 15 Reply 7, posted (10 years 4 months 13 hours ago) and read 3401 times:
I'm glad to hear you've never had to lower your Dash-8's landing gear using the "lawnmower cords"....and I hope you never will.
Thanks for the information about where the cords are located, and the other alternate means of lowering the gear...the PTU.
Also, thanks for letting me know what an average airspeed is for landing a Dash-8 (with the understanding that each model is different).
I will always love the Dash-8 for many reasons, of which one is that I used to be a ramp rat for a small regional carrier called City Express, which flew both the Dash-8 and Dash-7. I was based with them at the Toronto Island Airport (YTC), back in the late 1980's.
On several occasions I had the pleasure of flying along in the jump seat of our aircraft (I believe our fleet had five Dash-8's and three Dash-7s), whenever a ramp worker was needed at one of our other destinations...Ottawa (YOW), Montreal (YUL), or Newark, NJ (EWR). Yes these aircraft are beautiful indeed!
I remember that one of our pilots - a Captain - always wore cowboy boots with his uniform (if he was wearing it), and he would sit back and relax in the cockpit with his right foot resting up against the instrument panel (on his panel's lower right side), while waiting for the passengers to start boarding. Well, his right boot started leaving it's mark over time. HeHeHe
Scootertrash, have you ever contributed to this progressive "intrument panel paint disease" in your Dash-8?
Here's some photos of how this occurs over time. It's sad...but there is a cure!
Scootertrash From United States of America, joined Aug 2001, 569 posts, RR: 10 Reply 8, posted (10 years 4 months 11 hours ago) and read 3379 times:
Not only do I wear cowboy boots to work, I have also contributed (probably a great deal) to what you refer to as "progressive instrument panel paint disease." Thanks, that really cracked me up! I going to bounce that one off our wrench benders. My company has actually installed non-skid pads on those portions of the panel which most often suffer from that affliction. Being rather long legged, my favored spots are the panel just to the left of the FO's side panel and where the instrument panel meets the center console, just below the Alternate Feather/Unfeather switches.