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Illustrated technical information covering Vol 2 Over 800 multi-choice systems questions Study notes and technical information Close up photos of internal and external components A compilation of links to major 737 news stories with a downloadable archive Illustrated history and description of all variants of 737 Detailed tech specs of every series of 737 Databases and reports of all the major 737 accidents & incidents General flightdeck views of each generation of 737's Description & news reports of Advanced Blended Winglets Press reports of orders and deliveries Articles from the press and official sources following the troubled history of the rudder PCU Details about 737 production methods A compilation of links to other sites with useful 737 content Get the book of the website A quick concise overview of the pages on this site

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*** Updated 24 Feb 2013 ***

Probes

This photo shows how close the air-bridge comes to the port instrument probes on the 1-500's. Care should be taken to park exactly in accordance with stand guidance as there is only a few inches of clearance.

I would recommend that you inspect the probes for damage if the jetty driver had any difficulty maneuvering onto your aircraft. This has greater importance these days with the introduction of RVSM airspace. Many airlines now paint a box around this "RVSM Critical Area" (Ref SRM 51-10-03) to indicate where no dents are allowable.

One of the improvements to the NG series was to move these probes further forward away from the jetty risk area.

Probes on a 737-3/4/500

 

Probes on the 737-NG

 

On the 1-500's, the LHS probes are from top to bottom:

  • Capts pitot and static & 1st aux static.

  • Alpha vane

  • F/O static & 2nd aux pitot

  • Temp probe

On the NG's, the LHS probes are from top to bottom:

  • Capts pitot.

  • Alpha vane

  • Temp probe
Notice that the pitot heat captions on the overhead panel (see below) are in a similar orientation. The elevator pitots are located on the tail-fin.

 

737-500 P/S heat panel

 

737-NG Probe heat panel
The 737-1/200 also has a second TAT probe on the RHS

 

Located on the stbd flightdeck wall, near the F/O's sun visor, the static source selector is only present on older aircraft (approx before l/n 1600 c1988).

 

Static Ports

 

737-1/500 Static port

This static port (737-3/4/500) is on the fwd stbd side of the fuselage and is showing signs of paint loss around it, possibly caused by ice or airflow.

The green discharge disc above it is from the crew oxygen bottle located in the forward cargo compartment. If the disc is missing it shows that the bottle has over temp'd or over pressured. Note it does not necessarily show that the bottle is empty (the bottle could have leaked through the masks on the flight deck), although if the disc is missing it most certainly will be empty.

 

    

737 NG Static Ports

Elevator Pitot

Elevator Pitot (All series)

TAT Probes

Aspirated TAT probes can either be identified visually (see below) or by the presence of a TAT test button on the pitot-static panel. To get an approximate OAT indication on the ground an air-conditioning pack must be on, whereas unaspirated probes require the pitot heat to be off.

Quote from the AMM: "The TAT probe gets bleed air from the APU duct in the keel beam. Bleed air into the probe makes a negative pressure inside the probe. The negative pressure pulls outside air across the sensing elements. This permits accurate temperature measurement when the airplane is on the ground or moving at low speed."

 

TAT Probe - Unaspirated

Perforated with large hole at rear

TAT Probe - Aspirated

Unperforated and no large hole at rear

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