View Full Version : TPMS
hetfield
26th Jul 2007, 16:08
How come Tyre Pressure Monitor Systems are federal law in US for all new cars and trucks beginning 01. September 2007, but not required on commercial aeroplanes?
enicalyth
27th Jul 2007, 16:37
A road vehicle rolls all the way to its intended destination on its tyres. In its simplest form TPMS measures differential rotation speeds. You could encumber it with nitrogen pressure sensing, temperature sensing, vibration sensing which may prevent an appalling roadtrain accident twixt Alice Springs and Tennant Creek. But to prevent an accident in the 45secs it takes an aircraft to travel 2000 metres before taking flight the first line of defence is the partnership of engineer and pilot who perform the pre-flight inspection. If at the back of your mind you have an idea that aircraft tyres are physically neglected and that furthermore the best way to mitigate the consequences is to calibrate and fit a sophisticated suite of testgear that has a measureable mean time between failures I have a better idea. Fit the gauges if they are practicable and make everyone's job easier but never for an instant abandon daily, flightly physical inspection by eye and by tools. And don't ape the habits of bad drivers. If drivers drove the way ground engineers prepared aircraft and pilots checked I'd be happier. Then my ten-year old boy would be a forty-two year old man.
hetfield
27th Jul 2007, 16:42
Do you know this?
http://www.flightsafety.org/ap/ap_sep93.pdf
hetfield
28th Jul 2007, 13:14
Come on, gimmie a brake. I'm only a skipper and want to know about my tyre(s) pressure, brake temperature and the heat condition in the wheel well. Am I demanding too much?
Kind regards
enicalyth
28th Jul 2007, 15:08
I can't believe I am so tetchy these days days. I feel really wretched now and I deserve to be. You are not just a skipper by the way. I thought Skippers were sandgropers..... ooh Lordy Caro, incoming!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Fargoo
28th Jul 2007, 19:27
I'm with Hetfield.
The airline I work for have tyre px specced on all the types it uses. Other airlines' aircraft I work on quite often have this option deleted.
Its all about costs, cheaper to not have all the bits associated with tyre px monitoring and not to have to maintain them.
Techman
28th Jul 2007, 19:35
It's a shame you deleted your post enicalyth. It's also a shame not everyone bothered to read it fully.
hetfield
29th Jul 2007, 17:47
Tyre failures on a commercial aeroplanes are a serious thread. Like Faroo said, it's all about cost.
Doe's your high tech Bus or Boeing have a tyre pressure indication?
If not, or inop, when have you tyres been checked for correct pressure?
May you depart without it, MEL?
Do we really need another Crash?
Bolty McBolt
30th Jul 2007, 00:24
How come Tyre Pressure Monitor Systems are federal law in US for all new cars and trucks beginning 01. September 2007, but not required on commercial aeroplanes?
Simple.
You dont go by road !!:ok:
How come Tyre Pressure Monitor Systems are federal law in US for all new cars and trucks beginning 01. September 2007, but not required on commercial aeroplanes?
Maybe it is because an Air Operator Certificate Holder has commercial aeroplanes maintained under an Approved System of Maintenance.
My (fairly new) Boeing does not have TPMS. But it is subject to a daily inspection by a licensed aircraft maintenance engineer prior to each day's flying, and it gets a once over at every turnaround from a licenced aircraft maintenance engineer...
I'd say the road transport people are catching up with us aviation people, rather than leaving us behind in the maintenance and safety stakes.
Dan Winterland
30th Jul 2007, 06:35
Quote: How come Tyre Pressure Monitor Systems are federal law in US for all new cars and trucks beginning 01. September 2007, but not required on commercial aeroplanes?
Maybe it's because the manufacturers of the aircraft systems haven't lobbied their freinds in congress to have it made law, unlike the vehicle system manufacturers (he said with his cynical hat on!).
hetfield
30th Jul 2007, 07:42
Maybe you change your mind after reading the mentioned accident report.
I read the FSF report, hetfield, and I must say I did not find it a compelling argument to have TPMS installed.
It might be a useful thing to have to break the error chain, but the thing that concerned me was that the crew asked for a top up before departure. Perceived time pressure intervened. The N bottles were an inconvenient distance away, the pax were late. There were CRM issues, there were training issues....
In particular, consider not retracting the gear if tyres/etc are suspect.
I'm wondering, if my tyres overheated, blew, and caught fire, if my brake temp indications would give me a hint?
hetfield
1st Aug 2007, 07:17
I agree with you, concerning crew action. I disagree concerning equipment of modern civilian jets.
Look at the recommendation of the report:
All transport aircraft should have
- wheel well overheat and fire detectors
- whell well fire protection
- brake temp indicators (in cockpit)
- tyre pressure indicators (in cockpit)
You know what my AIRBUS got? Only brake temperatur indication! And this may be legaly inop.:ugh:
You know what my AIRBUS got? Only brake temperatur indication! And this may be legaly inop.
Same on my B717. However the MEL condition is that the aircraft turnaround with brake temp inop is 50 minute turnarounds -- a significant disincentive for our operator!
Interestingly, the US ALPA is in agreeance with you. Their tech team commented on the 717's lack of TPMS when they flew a Boeing demonstrator at the type's introduction.
"Because of the short-range/high-cycle type of flying that this aircraft will perform, Boeing preferred steel brakes--they cost less than carbon brakes, which are lighter and are preferred for longer-range aircraft that make comparatively fewer landings. Brake temperatures are displayed, but tire pressure is not, even as an option. Full-time tire pressure monitoring, although an option often removed (not by pilots), can be very effective in preventing a high-speed abort for a tire failure because of low tire pressure--a fully preventable event, if only the flight crew is given the proper information."
cf.alpa.org/internet/alp/2000/marb717.htm
hetfield
1st Aug 2007, 16:17
Thx for that helpfull information.
Concerning brake temp indication as the only thing which is showing thermal situation in your wheel well. It's only little help, cause it will need some time until the heavy mass of brake discs are heated up in case of a fire. Guess in the meanwhile the cabin will have some black smoke......