Summary of the Problem.

TB 1--1520--240--20--121

(a) Same as paragraph 1a.

(b) Those aircraft that have a DD250 and are at Boeing Helicopters, Philadelphia will be in-

spected prior to ferry to final destination.

Maintenance Trainers (Category A and B). Same as paragraph 1a.

Components/Parts in Stock at All Levels (Depot and Others) including War Reserves. N/A.

Components/Parts in Work (Depot Level and Others). N/A.

Task/Inspection Suspense Date. Within the next 10 flight hours but no later than 15 June 2000.

3. Reporting Compliance Suspense Date. Report compliance in accordance with paragraph 14a no later

than 23 June 2000.

Summary of the Problem.

a. The H--47 community has reported several incidents in which the aircraft experienced uncomman-

ded maneuvers or flight control lock up while in flight. Contaminated hydraulic fluid is a factor which has been

present and may have contributed to the uncommanded maneuvers or flight control lock up. To resolve this

hydraulic fluid contamination factor, a periodic sampling interval of 50 flight hours or 100 calendar days for

the number one, number two, and utility hydraulic systems will be initiated.

For manpower/downtime and funding impacts, see paragraph 12.

The purpose of this Technical Bulletin is to require periodic sampling of hydraulic fluid for contamina-

tion.

End Items to be inspected . All H--47 Aircraft.

Assembly Components to be Inspected. N/A.

Parts to be Inspected . N/A.

Inspection Procedures.

a. A three ounce hydraulic fluid sample will be taken every 50 flight hours or 100 calendar days from

the aircrafts number one, number two, and utility hydraulic systems. The initial sample will be taken within

10 flight hours but no later than 15 June 2000. The three ounce hydraulic fluid samples will be taken in accor-

dance with Task 7-8.1 of TM 55-1520-240-23 or Task 7-11 of TM 1-1520-252-23. The samples will be sent

to the units designated Army Oil and Analysis Program (AOAP) laboratory for analysis.

NOTE

Correct hydraulic sampling procedures are paramount to a successful

sampling program. The majority of bad samples are the result of improp-

er sampling, inadequate draining and taking of samples.

b. Effective with this Technical Bulletin, all hydraulic fluid filter elements which are removed from the

aircraft for normal maintenance replacement will be sent to the units designated AOAP laboratory for analy-

sis.

c. All hydraulic test stands (Depot and Organizational), Auxiliary Ground Power Units (AGPU) and

Hydraulic Carts, will have fluid samples analyzed every seven calendar days.

d. Special samples will be taken whenever a major hydraulic component (for example; the pump, check

valve etc.) has failed, or whenever the hydraulic system is suspect.

Correction Procedures.

a. Currently the AOAP laboratories are able to test for water levels in hydraulic fluids. The AOAP labo-

ratories are also currently able to test for levels of particulate contamination (in parts per million) of specific

elements which include iron,aluminum, chromium, copper, silicon, sodium, nickel, and zinc.

(1) For aircraft systems using MIL--H--83282, the maximum limit for water is 350 parts per million.

For hydraulic fluid which has been verified by AOAP as exceeding 350 parts per milliion of water, change the