PITOT-STATIC PROBE - INSPECTION/CHECK
1. General
A. The inspection check visually inspects the pitot static probe for physical damage to the strut, head and precision-contoured surfaces and for foreign material in the static ports, drain hole and pitot opening. The pitot static probe should be replaced if it fails any of the visual inspections (AMM 34-11-11/401).
B. Fly Back Limits
(1)
Do these steps when you see pitot-static probe deterioration that you think is more than the inspection tolerances:
(a) You can dispatch the airplane from a base without maintenance facilities until one of these conditions occur: 1) 24 hours elapse 2) The airplane gets to a maintenance base.
(2)
Replace the pitot-static probe for one or more of these conditions:
(a)
The flight crew sees a cross panel airspeed difference that is more than stated below:
1) The airspeed difference must not be more than 3 knots when the airspeed is less than 250 knots and the altitude is below 20,000 feet.
(b)
There is structural damage to the pitot-static probe since the last flight.
2. Equipment and Materials
A. Assorted gages or wires - 0.004- to 0.020-inch, or Optical Micrometer - Model 966A1, Monocle Industries, Inc., P.O. Box 2426, Coppell, Texas 75019, or other suitable instrument, Pitot-Static Probe Tip Inspection Model 885N, Rosemount Aerospace, Inc., 14300 Judical Road, Burnsville, MN 55306-4898
3. Inspect Pitot Static Probe
NOTE: When performing the Aerodynamic Contour Condition check or the Pitot Tip Condition check (with or without an inspection kit), it is not necessary to remove the pitot static probe.
A. General Probe Conditions
(1)
Remove the pitot-static probe (AMM 34-11-11/401).
(2)
Visually inspect the pitot-static probe for physical damage to its precision-contoured surfaces and for foreign material in the static ports, drain hole and pitot opening. To remove the foreign material, refer to AMM 34-11-11/401.
(3)
Check for any detectable bending or twisting of the head or strut sections of the pitot-static probe.
B. Aerodynamic Contour Condition
(1)
Check the static pressure ports to make sure their edges remain perpendicular to the probe's machined contoured surface. Rounded or raised static port edges should not exceed 0.003 inch (Fig. 601).
(2)
Check for scratches, nicks or surface irregularities located within 0.5 inch of the static ports, and deeper than 0.015 inch.
(3)
Check for defects exceeding 0.025 inch over the rest of the head, and exceeding 0.125 on the strut section of the probe.
501
May 01/01 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 34-11-11 Page 601
C. Pitot Tip Condition (WITHOUT PITOT-STATIC PROBE INSPECTION KIT)
(1)
The leading edge lip of the pitot opening should be sharp. New tubes are sharpened to a
0.004 +0.002 flat. The tube must be removed if the lip has been eroded through wear, or dented by abuse, to the extent that the lip has a flatness greater than 0.015 inch. Figure 602 shows this condition.
(2)
The outer surface of the lip edge must be smooth. It cannot be curled or flared outward. This condition can be detected by sliding your fingernail along the outer surfaces at the tip. The tube should be removed if the lip edge is curled or flared outward. Figure 603 illustrates this condition.
(3)
The lip can have small inward dents which affect the roundness of the pitot opening, as shown in Fig. 604. The tube must be removed if the indentation exceeds 0.030 inch from the normal tip diameter. The dent may be at any location around the opening, but must not affect more than 20% of the lip circumference.
(4)
The leading edge lip can have small nicks or chips as shown in Fig. 605. The tube must be replaced if two of the nicks are between 0.025 and 0.035 inch deep. The tube must also be replaced if any one nick exceeds 0.035 inch deep.
(5)
Install or replace the pitot static probe (AMM 34-11-11/401).
D. Pitot Tip Condition (WITH PITOT-STATIC PROBE INSPECTION KIT)
(1)
Examine the pitot tip of the probe with the inspection kit.
(2)
Replace the pitot-static probe if the inspection shows an out of tolerance condition (AMM 31-11-11/401).
G40534
Inspection Criteria for Static Ports 501
34-11-11 Figure 601 May 01/01
Page 602
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
501 Chips Or Nicks In Probe Tip
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