This memo is in response to a request for additional information
in regards to Safety Recommendation number 99.371.
The Wichita Aircraft Certification Office (ACO) received the
following Safety Recommendation on October 1, 1999:
Safety Recommendation 99.371; "The Bureau of Air Safety
Investigation recommends that the Federal Aviation Administration
alert all operators to initiate an immediate wiring and fuel-line
inspection of the Beech 1900 fleet in Wing Zones 531 and 631 as a
matter of the highest priority."
The original 1900s and 190OCs (serial numbers beginning with "UA"
and "UB" respectively) use a fuel bladder versus a total wet wing
in the later 190OCs (serial numbers beginning with 'UC") and 1900D
series (serial numbers that begin with "UE"). The specific area of
concern for this Safety Recommendation is applicable only to the
'UC" serial numbered 190OCs and 1900D aircraft models because the
components involved in this incident are located elsewhere in the
Model 1900s and original 190OCs ('UA"s and "UB" s). However, there
are some wiring and fuel systems components in this general area in
these earlier model aircraft ("UA" and "UB" serial numbers) so the
review included them as well.
In the FAA's investigation, which included looking at the incident
pictures, reviewing new production 1900D aircraft and reviewing the
1900, 1900C and 1900D Maintenance Manuals, the following items were
noted:
a. The incident pictures revealed "tie-wrap" impressions on the
plumbing in the area where the arcing is believed to have occurred.
This indicates that at one time, the tie-wraps that are used to
construct the stand-offs for the electrical wiring were in
place.
b. The 1900 and 1900C Maintenance Manual in Section 5-20-02, page
5, (First 200-hour-interval detailed inspection) for item 13.b.
states "LEADING EDGE AND NACELLE PLUMBING AND WIRING Zone
inspection areas: 511, 521, 522, 531, 541, 611, 621, 622, 631 and
641. Wing panel inspection areas: 54, 55, 56, 57, 58, 59, 60, 61
(UA-1 and after, UB-1 and after); 23, 24, 25, 26, 27, 28 and 29
(UC-1 and after). b. Check the wiring for chafing and security of
attachment." In addition, on the same page of the same section for
item 14.a states, "PLUMBING Zone inspection areas: 531, 532, 631
and 632. Wing panel inspection areas: 4, 17, 18 (UA- 1 and after,
UB- 1 and after); 8, 9, 11, 12, 15, 18, 21, 23, 25, 29 (UC- 1 and
after). a. Visually check for leaks, chafing or damage and proper
attachment." This inspection is one of six that are to be repeated
every 1200 hours per section 5-20-00, page 3 of the same
manual.
c. The 1900D Maintenance Manual in Section 5-20-02, page 204,
(First 200-hour-interval detailed inspection) for item 9.b. states
"LEADING EDGE AND NACELLE PLUMBING AND WIRING Zone inspection
areas: 521, 621, 522 and 622. Panel inspection areas: 511, 611,
531AB and 631AB. b. Check the wiring for chafing and security of
attachment." In addition, on page 205 of the same section for item
14.a states, "PLUMBING Zone inspection areas: 500, 600, 730 and
740. Panel inspection areas. 531AT and 631A.T. a. Visually check
for leaks, chafing or damage and attachment." This inspection is
one of six that are to be repeated every 1200 hours per Section
5-20-00, page 204 of the same manual.
d. A FAA representative ran a search on the FAA Service Difficulty
Database for "chaffing". What was found were SDR items 162360 and
332583 (there were actually several more, but these were the most
relevant). Both of these items appeared to be different (one being
in the right outboard nacelle, the other being in the wheel well).
The FAA representative did not find any other occurrences of items
that resembled this particular scenario.
e. A FAA representative also visually inspected the new Model 1900D
aircraft that were coming off of the assembly line. The two
production aircraft that were inspected had the electrical wire
stand-offs in place, and the FAA representative concluded that
these stand-offs provided adequate clearance to the fuel
lines.
f. The FAA representative that was investigating this incident was
not aware of any instances where the plastic tie wraps that are
used for stand-offs have failed (without being cut by
something).
The FAA concludes that the Maintenance Manuals already provide for
wiring and fuel-line inspection of the Beech 1900, 1900C and 1900D
fleet in Wing Zones 531 and 63 1. These wiring and fuel-line
inspections are required by the same Maintenance Manuals to be
repeated every 1,200 hours. The FAA believes that these inspections
are adequate and that no additional Airworthiness Directive action
is required. Therefore, we recommend this Safety Recommendation be
closed.
