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ELT Question (737)  
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3390 posts, RR: 9
Posted (7 years 4 months 2 days 20 hours ago) and read 5283 times:

Well today during the turn we were giving one of our 737-200s a quick groom, and it was just us groomers in the rear cabin and some rampers down on the ground, as well as a mechanic in the bridge.

So we were working away and out of nowhere off goes an alarm type thing. The mechanic ran into the flt deck and turned it off, and the started yelling out the door at the ramp folks if they hit the plane. They said nobody hit anything that they know of, and then the mechanic came back and asked us if we saw/heard anything hit the plane, as the ELT had gone off and it is only designed to do that if the plane hits something hard enough.

He figured the only thing it could be was the jet beside us (a Jazz CRJ705 departing for Vancouver) that turned out from the terminal and gave us a good jetblast (I did feel the plane shake slightly and it was easily heard via the open door nearby). But I was thinking, I've never heard of an ELT going off on a hard landing, so how would some jetblast set it off? The jet did leave pretty much on time so I guess it was true that nobody hit the plane with any ramp vehicles or anything, atleast not hard enough to break anything...

Anyhow, long enough post. Looking forward to any replies from anyone with ELT and/or 737 experience...


CanadianNorth


What could possibly go wrong?
22 replies: All unread, jump to last
 
User currently offlineKELPkid From United States of America, joined Nov 2005, 6411 posts, RR: 3
Reply 1, posted (7 years 4 months 2 days 17 hours ago) and read 5265 times:

ELT's (at least the ones in GA planes  Wink ) go off far more often than the general public realizes...hard landings, people being careless with the ELT on the ground, etc. etc. Usually, the only audible sign of an ELT activation is when one tunes an air band radio to 121.5. Quite a few amateur radio 2-meter repeaters are also programmed to detect an ELT activation, and one that I know of even triangulates the signal and broadcasts a bearing to the ELT when it happens. Apart from that, you would have to have some sort of triangulation equipment (like the Swivel Chair Patrol, err, Civil Air Patrol) does to find it.


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 2, posted (7 years 4 months 2 days 11 hours ago) and read 5234 times:

Impact type ELT needs a felt impact to trigger if in Arm position.The Water activated needs to be immersed in water/liquid.

I don't know how a jet blast or a loading movement can trigger the ELT.Makes no sense.Unless someone triggered the ELT sw in the Flt deck.

regds
MEL



Think of the brighter side!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6411 posts, RR: 3
Reply 3, posted (7 years 4 months 2 days 5 hours ago) and read 5203 times:

Quoting HAWK21M (Reply 2):
mpact type ELT needs a felt impact to trigger if in Arm position.The Water activated needs to be immersed in water/liquid.

I don't know how a jet blast or a loading movement can trigger the ELT.Makes no sense.Unless someone triggered the ELT sw in the Flt deck.

Hi MEL, in regards to the original poster's question: are the evacuation alarm and ELT in any way interconnected in the 737?



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 4, posted (7 years 4 months 2 days 4 hours ago) and read 5198 times:

Quoting KELPkid (Reply 1):
Apart from that, you would have to have some sort of triangulation equipment (like the Swivel Chair Patrol, err, Civil Air Patrol) does to find it.

Not really, all you need is a hand held receiver, hold it up against your body, and turn around in circles. When the signal is quietest, its source is behind you. When I was an instructor at a small FBO I used this method to successfully find ELTs on the airport that had been accidentaly activated.



09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineKELPkid From United States of America, joined Nov 2005, 6411 posts, RR: 3
Reply 5, posted (7 years 4 months 2 days 4 hours ago) and read 5190 times:

Quoting Ralgha (Reply 4):
Not really, all you need is a hand held receiver, hold it up against your body, and turn around in circles. When the signal is quietest, its source is behind you. When I was an instructor at a small FBO I used this method to successfully find ELTs on the airport that had been accidentaly activated.

"Hi Bob, what you doing? It looks quite foolish..."

"Well John, it's called the ELT dance. We do it at this field anytime an ELT goes off to try to locate the source..."  laughing 



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineRalgha From United States of America, joined Nov 1999, 1614 posts, RR: 6
Reply 6, posted (7 years 4 months 2 days 3 hours ago) and read 5176 times:

So you would rather we wasted the taxpayer's money by doing nothing and waiting for the CAP or sheriff to drag themselves out there with DF gear to find something that we found in ~5 minutes? I'll keep that in mind next time. I'll ask them to send the bill to you instead of drawing on their normal funding to cover it if you like.


09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3390 posts, RR: 9
Reply 7, posted (7 years 4 months 2 days 3 hours ago) and read 5175 times:

Quoting HAWK21M (Reply 2):
Unless someone triggered the ELT sw in the Flt deck.

The only ones in the plane at the time were us in the back and the mechanic around the front door or on the bridge, so the flt deck was unoccupied at the time.

Quoting KELPkid (Reply 3):
Hi MEL, in regards to the original poster's question: are the evacuation alarm and ELT in any way interconnected in the 737?

Never thought of an evacuation alarm, but when the ELT supposedly went off an alarm could be heard reasonably loud in the last few rows where I was, and I'm assuming at the front as well by the immediate reaction of the mechanic...

Thanks for all the replies sofar...


CanadianNorth



What could possibly go wrong?
User currently offlineKELPkid From United States of America, joined Nov 2005, 6411 posts, RR: 3
Reply 8, posted (7 years 4 months 2 days 2 hours ago) and read 5173 times:

Quoting Ralgha (Reply 6):
So you would rather we wasted the taxpayer's money by doing nothing and waiting for the CAP or sheriff to drag themselves out there with DF gear to find something that we found in ~5 minutes? I'll keep that in mind next time. I'll ask them to send the bill to you instead of drawing on their normal funding to cover it if you like.

Not what I said at all. I just found some humor in the situation Big grin



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 9, posted (7 years 4 months 2 days 2 hours ago) and read 5166 times:

Quoting KELPkid (Reply 3):
are the evacuation alarm and ELT in any way interconnected in the 737?

No, they are not interconnected.

Quoting CanadianNorth (Reply 7):
Never thought of an evacuation alarm, but when the ELT supposedly went off an alarm could be heard reasonably loud in the last few rows where I was

The 737 is not typically equipped with an evacuation alarm, but it is a customer option. Typically, evacuations on board 737s are initiated with the flight deck providing a verbal command over the PA.



Release your seat-belts and get out! Leave everything!
User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 10, posted (7 years 4 months 2 days 1 hour ago) and read 5142 times:

Some of the newer ELTs have a speaker mounted next to the unit, so you can tell when it goes off. It's also used for testing the ELT. The number of beeps indicate a good or bad unit.

User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 11, posted (7 years 4 months 1 day 20 hours ago) and read 5117 times:

Excuse my ignorance, being an A&P student in my final semseter....but what the heck does ELT stand for? The A&P program didn't cover this in Airframe Electronics.


A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3390 posts, RR: 9
Reply 12, posted (7 years 4 months 1 day 19 hours ago) and read 5116 times:

Quoting AirframeAS (Reply 11):
but what the heck does ELT stand for

Emergency Locator Transmitter or something along those lines. Basically it gets installed on most aircraft and what it's supposed to do is be triggered by the plane crashing, and it sends out a signal so the search and rescue people can pick up the signal and use it to locate the aircraft.


CanadiaNorth



What could possibly go wrong?
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 13, posted (7 years 4 months 1 day 19 hours ago) and read 5113 times:

Quoting CanadianNorth (Reply 12):
Emergency Locator Transmitter

Ok, I am a moron! I should HAVE known that! They did teach that in the program, but only applied it to a Cessna.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineCanadianNorth From Canada, joined Aug 2002, 3390 posts, RR: 9
Reply 14, posted (7 years 4 months 1 day 17 hours ago) and read 5089 times:

Quoting AirframeAS (Reply 13):
They did teach that in the program, but only applied it to a Cessna.

They can be put on pretty much any aircraft type as far as I know, I've personally seen them on Cessnas, Helicopters and 737s.


CanadianNorth



What could possibly go wrong?
User currently offlineUnited757 From United States of America, joined Jul 2006, 103 posts, RR: 0
Reply 15, posted (7 years 4 months 1 day 17 hours ago) and read 5088 times:

Just the other day one went off at my flight school, we were taxing out when one of the fire trucks stopped us, and had us check our ELT. After that we kept tuning into 121.5 to see if they had found which plane it was. They were also making anouncments from time to time on the ground frequency asking people to check their ELT's.

User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 16, posted (7 years 4 months 1 day 14 hours ago) and read 5076 times:

Quoting KELPkid (Reply 3):
Hi MEL, in regards to the original poster's question: are the evacuation alarm and ELT in any way interconnected in the 737

There is No connection.

Quoting CanadianNorth (Reply 7):
The only ones in the plane at the time were us in the back and the mechanic around the front door or on the bridge, so the flt deck was unoccupied at the time.

Probably Malfunction.

Quoting Avt007 (Reply 10):
Some of the newer ELTs have a speaker mounted next to the unit, so you can tell when it goes off. It's also used for testing the ELT. The number of beeps indicate a good or bad unit.

The Unit [Impact type] is located at the Aft near the Empennage on a B737.The Speaker & Test/On switch is wirelocked in On position & located on P5 overhead panel.

Quoting AirframeAS (Reply 11):
Excuse my ignorance, being an A&P student in my final semseter....but what the heck does ELT stand for

http://en.wikipedia.org/wiki/Emergen...y_Position-Indicating_Radio_Beacon

regds
MEL



Think of the brighter side!
User currently offlineAirframeAS From United States of America, joined Feb 2004, 14150 posts, RR: 24
Reply 17, posted (7 years 4 months 18 hours ago) and read 5020 times:

Quoting HAWK21M (Reply 16):
http://en.wikipedia.org/wiki/Emergen...y_Position-Indicating_Radio_Beacon

Thanks for the link, Hawk. But I never use wikipedia for obvious reasons.



A Safe Flight Begins With Quality Maintenance On The Ground.
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 18, posted (7 years 4 months 17 hours ago) and read 5010 times:

Quoting HAWK21M (Reply 2):
Impact type ELT needs a felt impact to trigger if in Arm position.The Water activated needs to be immersed in water/liquid.

I' ve never seen a "water activated" ELT. Not on the B737 and not on a lot of other types I' ve worked on. ELTs can be activated either manually or automatically by the internal g-switch.

Are you sure you don' t mix it with the CVR and FDR???



This job sucks!!! I love this job!!!
User currently offlineMarkHKG From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 19, posted (7 years 4 months 17 hours ago) and read 5009 times:

Quoting Troubleshooter (Reply 18):

I' ve never seen a "water activated" ELT.

The cabin portable ELTs (the ones the flight attendants are meant to take with them) are frequently water activated. One of the more popular one requires the placement of the unit into an electrolyte solution (sea water or thin soup, urine, etc.). If you put it into the sea (like tying it to a raft) the tape automatically comes undone to deploy the antennae.

http://www.acrelectronics.com/pdfs/Y1-03-0090-2D.pdf



Release your seat-belts and get out! Leave everything!
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 20, posted (7 years 4 months 9 hours ago) and read 4984 times:

Quoting AirframeAS (Reply 17):
Thanks for the link, Hawk. But I never use wikipedia for obvious reasons

True.But some things are believable.

Quoting Troubleshooter (Reply 18):
I' ve never seen a "water activated" ELT. Not on the B737 and not on a lot of other types I' ve worked on. ELTs can be activated either manually or automatically by the internal g-switch.Are you sure you don' t mix it with the CVR and FDR???



Water Activated ELT is a portable unit.Our B737 Freighters have them.On ctc with water the cord holding the Antenna loosens & the Antenna goes to a vertical position as its spring loaded.There is a Water activating device that supplies charge to the ELT for transmission.


regds
MEL



Think of the brighter side!
User currently offlineTroubleshooter From Germany, joined Feb 2005, 423 posts, RR: 5
Reply 21, posted (7 years 4 months 5 hours ago) and read 4962 times:

Quoting MarkHKG (Reply 19):
The cabin portable ELTs (the ones the flight attendants are meant to take with them) are frequently water activated. One of the more popular one requires the placement of the unit into an electrolyte solution (sea water or thin soup, urine, etc.). If you put it into the sea (like tying it to a raft) the tape automatically comes undone to deploy the antennae.



Quoting HAWK21M (Reply 20):
Water Activated ELT is a portable unit.Our B737 Freighters have them.On ctc with water the cord holding the Antenna loosens & the Antenna goes to a vertical position as its spring loaded.There is a Water activating device that supplies charge to the ELT for transmission.

Thanks guys! I've never seen that type of ELT. Our aircrafts have all a fixed ELT installed.



This job sucks!!! I love this job!!!
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 22, posted (7 years 3 months 3 weeks 6 days 8 hours ago) and read 4886 times:

Quoting Troubleshooter (Reply 21):
Our aircrafts have all a fixed ELT installed

Our Freighter use both the Impact Type & water Activated type.
regds
MEL



Think of the brighter side!
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